Film forming method, film forming apparatus, pattern forming method, and manufacturing method of semiconductor apparatus

ABSTRACT

There is disclosed a film forming method comprising continuously discharging a solution adjusted so as to spread over a substrate by a given amount to the substrate through a discharge port disposed in a nozzle, moving the nozzle and substrate with respect to each other, and holding the supplied solution onto the substrate to form a liquid film, wherein a distance h between the discharge port of the nozzle and the substrate is set to be not less than 2 mm and to be in a range less than 5×10 −5  qγ (mm) given with respect to a surface tension γ (N/m) of the solution, discharge speed q (m/sec) of the solution continuously discharged through the discharge port, and a constant of 5×10 −5  (m·sec/N).

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional of application Ser. No. 10/927,141 filed Aug. 27,2004, now U.S. Pat. No. 7,312,018, which is a divisional of applicationSer. No. 10/352,954, filed Jan. 29, 2003, now U.S. Pat. No. 6,800,569,issued Oct. 5, 2004, and claims priority from prior Japanese PatentApplications No. 2002-22382, filed Jan. 30, 2002; No. 2002-31911, filedFeb. 8, 2002; and No. 2002-100516, filed Apr. 2, 2002. The entirecontents of the Japanese applications and application Ser. 10/352,954are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a film forming method comprising:moving a substrate and nozzle with respect to each other; droppingsolution onto the substrate from a solution discharge nozzle; andforming a liquid film of the solution on the substrate.

2. Description of the Related Art

To use a spin coating method in a lithography process and interlayerfilm formation, most of the solution dropped onto a substrate isdischarged off the substrate, and a film is formed with the remainingseveral percent of the solution. Therefore, there is much waste, and theenvironment is adversely affected. Moreover, there has been a problemthat turbulence is generated in an outer peripheral portion of a squaresubstrate or a circular substrate having a large diameter of 12 inchesor more, making the film thickness nonuniform in that portion.

As a method of uniformly coating the whole surface of the substratewithout wasting in Jpn. Pat. Appln. KOKAI Publication No. 2-220428, amethod is described which comprises: dropping resist from a large numberof nozzles arranged in one row; and spraying a gas or solution onto afilm forming surface from behind the nozzles to obtain a uniform film.Further, in Jpn. Pat. Appln. KOKAI Publication No. 6-151295, a largenumber of spray ports are disposed in a bar; and the resist is droppedonto the substrate from the ports to obtain a uniform film. Furthermore,in Jpn. Pat. Appln. KOKAI Publication No. 7-321001, a method isdescribed comprising: using a spray head in which a large number of jetholes are formed to spray the resist; and moving the head with respectto the substrate to coat the substrate. In all of these coatingapparatuses, a plurality of dropping or spray nozzles are transverselyarranged in a row, so as to scan the nozzles along the substrate surfaceand a the uniform film. In addition to these coating methods, there is amethod using one solution discharge nozzle, and scanning the nozzle toform a liquid film. This method has a problem that the treatment timeper substrate depends on the operation method of the nozzles, and theamount of solution used becomes enormous.

As an apparatus for solving the problem, in Jpn. Pat. Appln. KOKAIPublication No. 9-92134, a method is disclosed which comprises:reciprocating/moving the solution discharge nozzle over the substrate todrop the solution onto the substrate. The method further comprises:stopping liquid supply in each terminal end of the reciprocating/movingon the substrate; and re-supplying the solution in a start point to formthe coating film. However, the solution amount supplied onto thesubstrate slightly differs due to uneven liquid supply caused bystoppage and restart of liquid supply at the terminal end and startpoint, and a problem has occurred that film thickness uniformities ofthe liquid film and solid film formed from the liquid film aredeteriorated.

On the other hand, in Jpn. Pat. Appln. KOKAI Publication Nos.2000-77307, 2000-77326, 2000-79366, 2000-188251, 2001-148338,2001-168021, 2001-170546, 2001-176781, 2001-176786, 2001-232250, and2001-232269, a method is disclosed comprising: maintaining the dischargeof the solution even in a turn-back portion in the reciprocatingmovement of the solution discharge nozzle; and supplying a coating filmin which a film thickness distribution at an edge vicinity (the vicinityof turn-back of reciprocating movement) is not deteriorated. However, inthe coating apparatus described in these publications, a distancebetween the solution discharge nozzle and substrate is not considered.Depending on the discharge speed from the solution discharge nozzle,surface tension of the solution, and distance between the solutiondischarge nozzle and substrate, in a process of spread of liquid flowbefore the solution reaches the substrate, liquid drops are produced bythe surface tension of the liquid, and the liquid drops which havereached the substrate are sputtered, causing a problem of mist or vapor.

Moreover, in the above-described forming method in the liquid film, ineach region of the substrate surface to be treated, because ofdifferences of physical properties, discharge pressure of the nozzle,further variations in discharge amount of the solution, or turbulence ofair currents at the coating time, the film thickness of the liquid filmdoes not become uniform, and sometimes varies over the whole surface ofthe substrate. When a solvent in the liquid film is vaporized in thisstate, a film of a solid content (=solid film) is formed on thesubstrate with low flatness in accordance with the film thicknessdistribution of the liquid film.

Moreover, even when the liquid film is formed in a excellent flatnessstate, when a drying process is thereafter executed so as to vaporizethe solvent, aggregation occurs toward the middle portion of thesubstrate. In this manner, the solid content moves with the movement ofthe liquid film in a transverse direction, and a difference in filmthickness is generated in the movement direction.

When a such photo resist film which is formed using the such method issubjected to exposure and development processes to form a pattern, acritical dimension (CD) error is generated in the pattern. In a processin which this pattern is used as a mask to subject a lower layer film(e.g.: insulating film, and conductive wiring film) to etchingprocessing, the CD error is further enlarged. This was an effect ofreducing the yield.

As disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2001-237179, withrespect to the variation in thickness of the liquid film, there hasheretofore been a method comprising: forming the liquid film;subsequently exposing the film to a solvent vapor to promote fluidity ofthe solution; and performing a so-called leveling treatment so that thesurface of the liquid film is flatted by the surface tension.

However, in the prior-art leveling treatment, the solvent isunnecessarily supplied to the surface of the liquid film, and the filmthickness is uneven. Inclination is generated in the film thickness ofthe liquid film (e.g., peripheral edge) by an inadequate condition.

Additionally, a manufacturing process of the semiconductor apparatuscomprises: coating the substrate surface with a resist solution in whichresist materials such as a resin, dissolution inhibitor (dissolutioninhibitor group), and acid generating material (acid generation group)are dissolved in organic solvent (ethyl lactate, etc.) to form theliquid film; and subsequently evaporating the solvent in the liquid filmto form the resist film. The resist film formed on the substrate isexposed to light, then bake-treated, cooled, and developed to form aresist pattern.

Some of the resist patterns formed as described above have a problemthat the upper part of the resist pattern is rounded. Since the uppersurface of the resist film is exposed to a developing liquid for a longtime, the upper part becomes rounded. To solve this problem, a layercontaining many dissolution inhibitor can be formed in the surfacelayer.

However, to form the layer containing many dissolution inhibitor in thesurface layer, a prior art method has to comprise: coating the substratewith a first resist solution film; baking and forming a first resistfilm; coating the first resist film with a second resist solution filmusing a resist solution which containing the dissolution inhibitor morethan the resist solution used in forming the first resist film; andbaking and forming the second resist film. In this method, two resistfilms have to be separately formed, which lengthens manufacturing time.

As a prior-art method of forming the coating film on the substrate,there is a method comprising: relatively moving a discharge nozzle whichdischarges a given amount of solution on the substrate; discharging thesolution over the whole surface of the substrate to form a liquid film;and thereafter evaporating the solvent by an appropriate dry method toform the film. In this method, a solution which has a small solidcontent and has a low viscosity in a range of about 0.001 Pa·s to 0.010Pa·s (1 cp to 10 cp) is used. When the liquid film is formed on asubstrate having a stepped portion in this coating method, the formedliquid film is fluidized by gravity, and a concave/convex portion issmoothed. A difference is generated in the thickness of the finallyprepared coated film, that is, the film thickness of the concave portionincreases and that of the convex portion decreases. As a result, thereis a problem that a film having a uniform thickness cannot be formed onthe substrate surface.

BRIEF SUMMARY OF THE INVENTION

(1) According to one aspect of the present invention, there is provideda film forming method of discharging a solution from a discharge port ofa nozzle onto the substrate, and then providing relative movementbetween the nozzle and the substrate while keeping the liquiddischarging on the substrate, so as to form a liquid film on thesubstrate,

wherein a distance h between the discharge port of the nozzle and thesubstrate is set to be not less than 2 mm and to be less than Aqγ (mm),

wherein q (m/sec) denotes a discharge speed of the solution continuouslydischarged through the discharge port,

γ (N/m) denotes a surface tension of the solution, and

A (m·sec/N) is 5×10⁻⁵.

(2) According to another aspect of the present invention, there isprovided a film forming method comprising:

registering a surface tension γ (N/m) of a solution adjusted so as tospread over the substrate by a given amount;

calculating a distance h between a discharge port of a nozzle and asubstrate, which is not less than 2 mm and is less than 5×10⁻⁵ qγ (mm),from a discharge speed q (m/sec) of the solution continuously dischargedto the substrate through the discharge port of the nozzle, surfacetension γ (N/m) of the solution, and constant of 5×10⁻⁵ (m·sec/N); and

discharging a solution from a discharge port of a nozzle onto thesubstrate, and then providing relative movement between the nozzle andthe substrate while keeping the liquid discharging on the substrate.

(3) According to further aspect of the present invention, there isprovided a film forming method comprising: combining a linear movementin a column direction in which a nozzle passes along a substrate fromone end of the substrate to the other end of the substrate with amovement in a row direction inside or outside the substrate to move thenozzle and substrate with respect to each other; continuouslydischarging a solution adjusted so as to spread over the substrate by agiven amount through a discharge port disposed in the nozzle; holdingthe discharged solution on the substrate; and forming a liquid film,further comprising:

obtaining a deviation amount of a discharge amount of the solution froma desired value with respect to a discharge position of the solution,when the solution is discharged onto the substrate from the nozzlemoving in a first column; and

controlling the discharge amount in an arbitrary position in a secondcolumn so as to compensate for the deviation amount obtained in anadjacent discharge position on the first column, when the solution isdischarged onto the substrate from the nozzle moving on a second columndisposed adjacent to the first column.

(4) According to still another aspect of the present invention, there isprovided a film forming method comprising: moving a nozzle in a diameterdirection of a substrate over the substrate which rotates; continuouslydischarging a solution adjusted so as to spread over the substrate by agiven amount through a discharge port disposed in the nozzle; andholding the supplied solution on the substrate to form a liquid film,further comprising:

obtaining a deviation amount of a supply amount of the solution from adesired value with respect to a discharge position of the solution, whenthe solution is supplied onto the substrate from the nozzle; and

controlling the supply amount of the solution discharged to a firstposition, so as to compensate for the deviation amount in a secondposition which is disposed adjacent to the first discharge position inthe diameter direction of the substrate and to which the solution hasalready been discharged, during the supply of the solution into thefirst position of the substrate from the nozzle.

(5) According to further aspect of the present invention, there isprovided a film forming method comprising: combining a linear movementin a column direction in which a nozzle passes along a substrate fromone end of the substrate to the other end of the substrate with amovement in a row direction inside or outside the substrate to move thenozzle and substrate with respect to each other; continuouslydischarging a solution adjusted so as to spread over the substrate by agiven amount through a discharge port disposed in the nozzle; holdingthe discharged solution on the substrate; and forming a liquid film,further comprising:

cutting off the solution discharged onto the substrate from the nozzleso that a supply start point and supply end point of the solutiondischarged onto the substrate from the nozzle reach a liquid film edgeforming position apart from each edge of the substrate by a given widthd during the movement of the nozzle in the column direction.

(6) According to further aspect of the present invention, there isprovided a film forming method comprising: combining a linear movementof a column direction in which a nozzle passes along a circularsubstrate from one end of the circular substrate through the other endof the substrate with a movement of a row direction in the vicinity ofan edge of the circular substrate to move the nozzle and substrate withrespect to each other; continuously discharging a solution adjusted soas to spread over the circular substrate by a given amount to thesubstrate through a discharge port disposed in the nozzle; holding thedischarged solution onto the substrate; and forming a liquid film overthe whole surface of the substrate to an end position from a startposition,

wherein a movement speed of the column direction of the nozzle in thevicinity of the start position is set to be lower than the movementspeed of the column direction of the nozzle in a middle position of thesubstrate; and

the movement speed of the column direction of the nozzle in the vicinityof the end position is set to be higher than the movement speed of thecolumn direction of the nozzle in the middle position of the substrate.

(7) According to further aspect of the present invention, there isprovided a film forming method comprising: combining a linear movementof a column direction in which a nozzle passes along a circularsubstrate from one end of the circular substrate through the other endof the substrate with a movement of a row direction in the vicinity ofan edge of the circular substrate to move the nozzle and substrate withrespect to each other; continuously discharging a solution adjusted soas to spread over the circular substrate by a given amount to thesubstrate through a discharge port disposed in the nozzle; holding thedischarged solution onto the substrate; and forming a liquid film overthe whole surface of the substrate to an end position from a startposition,

wherein a movement distance of the row direction of the nozzle in thevicinity of the start position is set to be longer than the movementdistance of the row direction of the nozzle in a middle position of thecircular substrate; and

the movement distance of the row direction of the nozzle in the vicinityof the end position is set to be shorter than the movement distance ofthe row direction of the nozzle in the middle position of the substrate.

(8) According to further aspect of the present invention, there isprovided a film forming method comprising: combining a linear movementof a column direction in which a nozzle passes along a circularsubstrate from one end of the circular substrate through the other endof the substrate with a movement of a row direction in the vicinity ofan edge of the circular substrate to move the nozzle and substrate withrespect to each other; continuously discharging a solution adjusted soas to spread over the circular substrate by a given amount to thesubstrate through a discharge port disposed in the nozzle; holding thedischarged solution onto the substrate; and forming a liquid film overthe whole surface of the substrate to an end position from a startposition,

wherein a time interval from when the solution supply to the substrateby the movement of the column direction of the nozzle including themovement of the row direction of the nozzle is temporarily discontinueduntil the solution supply to the substrate by the movement of the columndirection of the nozzle is restarted is set to be constant.

(9) According to one aspect of the present invention, there is provideda film forming method comprising:

forming a liquid film constituted of a solution including a firstsolvent and solid content on a substrate;

containing the substrate in a container;

starting a leveling treatment to flat the surface of the liquid film ina state in which an atmosphere including a second solvent is formed inthe container;

measuring flatness of the surface of the liquid film during the levelingtreatment;

controlling at least one of the atmosphere in the container andtemperature of the substrate based on the measured flatness during theleveling treatment to enhance the flatness of the surface of the liquidfilm;

ending the leveling treatment; and

forming a solid film including the solid content on the substrate.

(10) According to further aspect of the present invention, there isprovided a film forming method comprising:

forming a liquid film including a solid content and solvent on asubstrate;

starting a drying treatment to remove the solvent in the liquid film;

measuring flatness of the surface of the liquid film during the dryingtreatment;

controlling at least one of the atmosphere of environment in which thesubstrate exists, temperature of the substrate, and rotation speed ofthe substrate based on the measured flatness during the drying treatmentto enhance the flatness; and

ending the drying treatment to form a solid film including the solidcontent on the substrate.

(11) According to one aspect of the present invention, there is provideda film forming apparatus comprising:

a support unit to support a substrate on the surface of which a liquidfilm including a first solvent is formed;

a container including the support unit disposed in an inner space;

a gas supply unit which includes a discharge port and which supplies gasincluding a second solvent into the container through the dischargeport;

an exhaust unit which exhausts air from the atmosphere in the container;

an optical system which irradiates the liquid film on the substratesupported on the support unit with light, receives reflected light fromthe liquid film, and obtains reflected light intensity; and

an analysis unit which analyzes the reflected light intensity obtainedby the optical system to measure flatness of the liquid film surface andwhich controls the exhaust unit and gas supply unit so as to enhance themeasured flatness.

(12) According to another aspect of the present invention, there isprovided a film forming method comprising:

forming a liquid film including a solution in which a first material isdissolved in a solvent on a substrate;

removing the solvent from the liquid film, until a substrate side of theliquid film solidifies and the solvent remains on a side opposite to thesubstrate side;

supplying a second material into the liquid film in a state in which thesolvent remains in a surface layer of the liquid film; and

removing the solvent remaining in the liquid film to form a solid film.

(13) According to further aspect of the present invention, there isprovided a film forming method comprising:

preparing a substrate which includes a concave/convex portion having astepped portion height of d and in which a rate of an area of the convexportion to the whole area is a (1>a>0) and a rate of an area of theconcave portion to the whole area is 1−a;

discharging a solution in which a solid content is dissolved in asolvent, moving a discharge nozzle and substrate with respect to eachother, and forming a liquid film on the substrate; and

removing the solvent in the liquid film, and forming a solid filmincluding the solid content,

wherein the liquid film is formed so that a thickness h of the liquidfilm satisfies a relation of h>(11−a)d.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a diagram showing a schematic constitution of a liquid filmforming apparatus according to a first embodiment;

FIGS. 2A to 2D are sectional views showing a film forming processaccording to the first embodiment;

FIG. 3 is a diagram showing concept of an observation system for use inobtaining a distance between a discharge port of a solution dischargenozzle and a substrate;

FIG. 4 is a diagram showing a relation of a discharge speed of thesolution with a distance Hp from the discharge port in a liquid dropstate;

FIG. 5 is an explanatory view showing definition of a region D in whichspread of the solution discharged through the discharge port isstabilized;

FIG. 6 is an enlarged view of a section of the discharge port of thesolution discharge nozzle;

FIG. 7 is a diagram showing a relation of a film thickness distributionin a wafer surface to a distance h between the discharge nozzle of thesolution discharge nozzle and the substrate;

FIG. 8 is a diagram showing a relation of the number of particles perwafer with respect to distance h between the discharge port andsubstrate;

FIG. 9 is an explanatory view of a method of calculating a dischargespeed q of the solution;

FIG. 10 is a diagram showing a liquid film thickness (supply amount)with respect to a discharge position, when a liquid film is formed by aPID control;

FIG. 11 is a diagram showing a liquid film thickness (supply amount)with respect to the discharge position, when the liquid film is formedby a control method according to a second embodiment;

FIG. 12 is a diagram showing a film with respect to the dischargeposition of a solid film obtained by removing a solvent in the liquidfilm formed by the control method according to the related art andpresent embodiment;

FIGS. 13A, 13B are diagrams showing a schematic constitution of a liquidfilm forming apparatus according to a third embodiment;

FIG. 14 is a diagram showing an installation relation of a shutterposition with respect to a track of the solution discharge nozzle;

FIGS. 15A, 15B are diagrams showing an error of a coat region generatedin a shutter;

FIG. 16 is a diagram showing an edge profile of the liquid film formedby a related-art shutter position;

FIG. 17 is a diagram showing the edge profile of the liquid film formedby the shutter position according to the present embodiment;

FIGS. 18A, 18B are explanatory views of a force applied to the liquidfilm edge at a substrate rotation time;

FIGS. 19A, 19B are diagrams showing the schematic constitution of theliquid film forming apparatus according to the third embodiment;

FIGS. 20A, 20B are diagrams schematically showing a spread state of aliquid line applied in a first column at a coating time of a secondcolumn, and boundary of a unit liquid film in the finally obtainedliquid film in a coating start/end portion at a time of preparation ofthe liquid film using the coating apparatus of FIG. 1 according to afourth embodiment;

FIGS. 21A, 21B are diagrams schematically showing the spread state ofthe liquid line applied in the first column at the coating time of thesecond column, and boundary of the unit coat film in the finallyobtained liquid film in the vicinity of a substrate center at thepreparation time of the liquid film using the coating apparatus of FIG.1 according to the fourth embodiment;

FIG. 22 is a diagram showing a relative thickness of a row direction ofthe film formed according to the related art and fourth embodiment;

FIG. 23 is a schematic diagram showing an apparatus for treating theliquid film on the substrate according to a fifth embodiment;

FIG. 24 is a plan view showing a schematic constitution of a temperaturecontrol plate according to the fifth embodiment;

FIG. 25 is a diagram relating to a treatment method of the liquid filmon the substrate in the fifth embodiment;

FIG. 26A is a diagram showing a change of the film thickness of theliquid film in each position on the substrate with time in a levelingtreatment according to the fifth embodiment;

FIG. 26B is a diagram showing a change of solvent concentration in gassupplied into a chamber with time in the leveling treatment according tothe fifth embodiment;

FIG. 26C is a diagram showing a change of temperature of middle andperipheral edge plates in the leveling treatment according to the fifthembodiment;

FIG. 27A is a diagram showing the change of the film thickness of theliquid film in each position on the substrate with time in the levelingand drying treatments according to the fifth embodiment;

FIG. 27B is a diagram showing the change of pressure in the chamber withtime in the leveling and drying treatments according to the fifthembodiment;

FIG. 27C is a diagram showing the change of temperature of middle andperipheral edge plates in the leveling and drying treatments accordingto the fifth embodiment;

FIG. 28A is a diagram showing the change of the film thickness of theliquid film in each position on the substrate with time in the levelingand drying treatments according to the fifth embodiment;

FIG. 28B is a diagram showing the change of the film thickness of theliquid film in each position on the substrate with time in therelated-art leveling and drying treatments;

FIG. 28C is a diagram showing the change of the film thickness of theliquid film in each position on the substrate with time in therelated-art leveling and drying treatments;

FIGS. 29A, 29B are diagrams showing effects of the fifth embodiment;

FIG. 30 is a schematic diagram showing an apparatus for treating theliquid film on the substrate according to a change example of the fifthembodiment;

FIG. 31A is a diagram showing the change of the film thickness of theliquid film in each position on the substrate with time in the levelingtreatment according to the fifth embodiment;

FIG. 31B is a diagram showing the change of solvent concentration in gassupplied into the chamber with time in the leveling treatment accordingto the fifth embodiment;

FIG. 31C is a diagram showing the change of temperature of the middleand peripheral edge plates in the leveling treatment according to thefifth embodiment;

FIG. 32 is a schematic diagram showing the apparatus for treating theliquid film on the substrate according to a modification example of thefifth embodiment;

FIG. 33A is a diagram showing the change of the film thickness of theliquid film in each position on the substrate with time in the levelingand drying treatments according to the fifth embodiment;

FIG. 33B is a diagram showing a change of a flow rate of N₂ gas suppliedinto the chamber with time in the leveling and drying treatmentsaccording to the fifth embodiment;

FIG. 33C is a diagram showing the change of temperature of the middleand peripheral edge plates in the leveling and drying treatmentsaccording to the fifth embodiment;

FIG. 34A is a diagram showing the change of the film thickness of theliquid film in each position on the substrate with time in the levelingand drying treatments according to the fifth embodiment;

FIG. 34B is a diagram showing the change of the flow rate of N₂ gassupplied into the chamber with time in the leveling and dryingtreatments according to the fifth embodiment;

FIG. 34C is a diagram showing the change of temperature of the middleand peripheral edge plates in the leveling and drying treatmentsaccording to the fifth embodiment;

FIG. 35 is a schematic diagram showing the apparatus for treating theliquid film on the substrate according to a modification example of thefifth embodiment;

FIG. 36 is a schematic diagram showing the apparatus for treating theliquid film on the substrate according to the modification example ofthe fifth embodiment;

FIG. 37A is a diagram showing the change of the film thickness of theliquid film in each position on the substrate with time in the levelingand drying treatments according to the fifth embodiment;

FIG. 37B is a diagram showing the change of the pressure in the chamberwith time in the leveling and drying treatments according to the fifthembodiment;

FIG. 37C is a diagram showing a change of rotation speed of thesubstrate in the leveling and drying treatments according to the fifthembodiment;

FIG. 38A is a diagram showing the change of the film thickness of theliquid film in each position on the substrate with time in the levelingand drying treatments according to the fifth embodiment;

FIG. 38B is a diagram showing the change of the flow rate of N₂ gassupplied into the chamber with time in the leveling and dryingtreatments according to the fifth embodiment;

FIG. 38C is a diagram showing the change of rotation speed of thesubstrate in the leveling and drying treatments according to the fifthembodiment;

FIG. 39A is a diagram showing the change of the film thickness of theliquid film in each position on the substrate with time in the levelingand drying treatments according to the fifth embodiment;

FIG. 39B is a diagram showing the change of the flow rate of N₂ gassupplied into the chamber with time in the leveling and dryingtreatments according to the fifth embodiment;

FIG. 39C is a diagram showing the change of rotation speed of thesubstrate in the leveling and drying treatments according to the fifthembodiment;

FIG. 40A is a diagram showing the change of the film thickness of theliquid film in each position on the substrate with time in the levelingand drying treatments according to the fifth embodiment;

FIG. 40B is a diagram showing the change of rotation speed of thesubstrate in the leveling and drying treatments according to the fifthembodiment;

FIGS. 41A to 41E are process sectional views showing a manufacturingprocess of a semiconductor apparatus according to a sixth embodiment;

FIG. 42 is a diagram showing a schematic constitution of the liquid filmforming apparatus according to the sixth embodiment;

FIG. 43 is a diagram showing a forming process of the liquid film usingthe liquid film forming apparatus shown in FIG. 42;

FIG. 44 is a diagram showing a shape of a resist pattern prepared from aresist film formed in a related-art method;

FIG. 45 is a sectional view showing the shape of the resist patternprepared using the resist film having a profile which has a higherdissolution inhibitor material concentration closer to the surface;

FIGS. 46A to 46C are a process sectional view showing the manufacturingprocess of the semiconductor apparatus according to a seventhembodiment;

FIG. 47 is a diagram showing a distribution of film thickness directionof oxygen and carbon with respect to Si in an interlayer insulatingfilm;

FIGS. 48A to 48E are a process sectional view showing the manufacturingprocess of the semiconductor apparatus according to an eighthembodiment;

FIGS. 49A to 49C are a process sectional view showing the manufacturingprocess of the semiconductor apparatus according to a ninth embodiment;

FIG. 50 is a diagram showing a schematic constitution of a pressurereduction drying treatment unit according to the ninth embodiment;

FIGS. 51A to 51C are a sectional view showing the film thicknessdistribution of the resist film formed on the substrate which has astepped portion;

FIG. 52 is a graph showing a ratio of a film thickness difference withrespect to an average film thickness;

FIG. 53 is a sectional view showing the film thickness distribution ofthe resist film formed on the substrate according to the ninthembodiment;

FIG. 54 is a characteristic diagram showing dependence of fluidity in anedge portion on the liquid film thickness; and

FIG. 55 is a characteristic diagram showing dependence of film thicknessuniformity of a convex portion in the whole substrate surface on theliquid film thickness.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention will be described hereinafter withreference to the drawings.

FIRST EMBODIMENT

FIG. 1 is a diagram showing a schematic constitution of a liquid filmforming apparatus according to a first embodiment. FIGS. 2A to 2D aresectional views showing a film forming process according to the firstembodiment of the present invention.

As shown in FIG. 1, a substrate 11 is horizontally laid on a substratemovement mechanism (not shown). A solution discharge nozzle 12 isdisposed above the substrate 11. The solution discharge nozzle 12reciprocates/moves in a direction crossing at right angles to a movementdirection of the substrate 11 by a nozzle movement mechanism (notshown). The solution discharge nozzle 12 includes a discharge portthrough which a solution 14 supplied from a solution supply pump 13 isdischarged with respect to the substrate 11.

A method of forming a liquid film on the substrate 11 comprises:discharging the solution 14 onto the substrate 11 through a dischargeport of the solution discharge nozzle 12; reciprocating/moving thesolution discharge nozzle 12 in a column direction; and linearlydischarging the solution onto the substrate 11. Moreover, when thesolution discharge nozzle 12 is positioned in a region other than aregion on the substrate 11 or outside a desired film forming region inthe substrate, the substrate 11 is moved in a row direction crossing atright angles to the column direction of the solution discharge nozzle12. Note that numeral number 15 in FIG. 1 denotes the track of thedischarged port on the substrate.

The solution linearly supplied onto the substrate 11 spreads by fluidityof the solution itself, and linear solutions disposed adjacent to oneanother join up, forming liquid film 16.

When the nozzle moves in the row direction as one direction to a liquidfilm forming end position from a liquid film forming start position, thesupply of the solution is performed with respect to substantially thewhole substrate 11, and the liquid film 16 is formed substantially overthe whole surface of the substrate 11 (FIG. 2A).

According to circumstances, the unit of FIG. 1 or apparatus (not shown)is used to perform a leveling treatment by leaving the film to stand inan atmosphere containing a solvent, and the surface of the liquid film16 is flatted (FIG. 2B). That is, when the solution discharges, thedischarge amount fluctuates, and a concave/convex portion is formed inthe surface of a liquid film 16. Then, if necessary, first the levelingtreatment is performed to flat the surface of the liquid film 16.

The substrate 11 is conveyed into a drying apparatus (not shown). Thesolvent in the liquid film 16 is removed by a pressure reduction orheating mechanism in the drying apparatus (FIG. 2C). A solid film 17having a predetermined thickness is formed on the substrate 11 (FIG.2D).

In the present embodiment, a procedure will be described comprising:optimizing a distance between the discharge port of the solutiondischarge nozzle 12 and the substrate 11 and produced position of liquiddrops; and supplying the solution onto the substrate from the solutiondischarge nozzle in this state, so that a satisfactory film thicknessdistribution having few defects is provided.

FIG. 3 is a diagram showing the concept of an observation system for usein obtaining the distance between the discharge port of the solutiondischarge nozzle and the substrate.

As shown in FIG. 3, a laser light source 21 and video camera forobservation 22 are disposed so as to hold the solution 14 dischargedthrough the discharge port of the solution discharge nozzle 12. It caneasily be judged whether the solution 14 discharged through thedischarge port has a liquid drop state by judging whether or not thelaser beam emitted to the solution 14 is scattered. A region in whichscattering is confirmed is regarded as a liquid drop forming region.

This observation optical system was used to conduct an experiment inwhich a relation of a discharge speed with a distance Hp from thedischarge port in the liquid drop state was obtained with respect to aresist solution including ethyl lactate in the solvent and including asolid content of 2%. Note that the surface tension of the resistsolution is 30×10⁻³ N/m and this is substantially the same as that ofthe solvent.

FIG. 4 shows the relation of the discharge speed with the distance Hpfrom the discharge port through which the solution is in the liquid dropstate. As shown in FIG. 4, it has been found that the discharge speedhas a proportional relation with the distance Hp for the resist solutionused in the experiment. FIG. 4 also shows a result of similarmeasurement performed with respect to pure water. With water, theproportional relation is obtained between the discharge speed anddistance Hp. In addition to these solutions, an experiment was alsocarried out with respect to various solutions of solvents havingdifferent surface tensions, such as methanol (surface tension=22.6×10⁻³N/m) and hexane (surface tension=18.4×10⁻³ N/m). In all experiments, aproportional relation was obtained. From these proportional relations, arelation of a discharge speed q (m/sec) from the solution dischargenozzle with the distance Hp (mm) is further represented by the followingequation (2) using a surface tension γ (N/m) of the solution.Hp≧5×10⁻⁵ qγ  (1)wherein a dimension of a constant 5×10⁻⁵ is m·sec/N.

It is seen from the equation (1) that the distance h between thedischarge port of the solution discharge nozzle and the substrate is asfollows in supplying the solution having the surface tension γ (N/m)onto the substrate at the discharge speed q (m/sec):h<5×10⁻⁵ qγ≦Hp  (2)

In the present example, in order to obtain a liquid film having anaverage thickness of 15 μm, a constant movement speed of the solutiondischarge nozzle on the substrate was set to 1 m/sec, a pitch of liquidlines on the substrate was set to 0.4 mm, and the resist solution(surface tension=30×10⁻³ N/m) including the solid content of 2% wasdischarged through the discharge port having a diameter of 40 μm at adischarge speed of 4.77 m/s. In this case, from the equation (2), anupper limit h_(max) of the distance h was determined as follows:hmax<0.05 [m·s/N]×4.77 [m/s]×30×10⁻³ [N/m]=7.16 [mm]  (3)

A lower limit of the distance between the discharge port of the solutiondischarge nozzle and the substrate was determined as a distance toobtain a region D in which the spread of the solution discharged throughthe discharge port is substantially stabilized. FIG. 5 shows a definedregion of the stabilized region D. The solution 41 discharged through adischarge port 21 of the solution discharge nozzle 12 rapidly spreadsimmediately after the discharge, thereafter slowly spreads, and reachesthe substrate 11. The spread differs according to diameter, shape (taperangle), and length of the discharge port 21 shown in FIG. 6, andviscosity of the solution. In the above-described coating method, adiluted solution is obtained at about several times 10⁻³ Pa·s. Moreover,the discharge port 21 of the solution discharge nozzle 12 having a shapeof (length of discharge port)/(diameter of discharge port)≧2 and a taperangle of 70° to 110° was used. Moreover, the discharge port 21 having adiameter of about 20 to 100 μm was used.

Note that the stabilized region D is defined as a region where a spreadwidth of 0.8 D_(W) or more is obtained with respect to a spread widthD_(W) of the solution discharged in h=5×10⁻⁵ qγ. The viscosity of thesolution was set to a range of 1 to 8×10⁻³ Pa·s, the discharge portshape of the solution discharge nozzle (length of dischargeport)/(diameter of discharge port) was set to a range of 2 to 5, and thetaper angle θ of the discharge port was set to a range of 70° to 110°.In these ranges, a plurality of nozzles were manufactured on trial inwhich the diameter of the discharge port was changed in a range of 20 to100 μm. The observation system shown in FIG. 3 was used to change thedischarge speed and measure the distance to the region D from thedischarge port. It has been found that the liquid spread is influencedparticularly by the discharge speed and the taper angle of the dischargeport, but the stabilized region D is obtained in any condition when thedistance from the discharge port was between 1 and 2 mm. It wasconfirmed that the stabilized region D was reached at h=1 mm, but withthe discharge in this state, the solution reaching the substrate bouncesback and dirties the surface of the nozzle disposed opposite thesubstrate. The distance h was changed to confirm the degree ofcontamination, and it has been found that the problem can be solved bymaking the distance h of 2 mm or more. From these studies, the lowerlimit of the distance between the solution discharge nozzle andsubstrate may be set to 2 mm. Note that with the supply of the solutiononto the substrate at a distance of 2 mm or less, the spread of thesolution on the substrate by the fluidity cannot sufficiently beobtained, or the nozzle is contaminated. Therefore, uniformity of theliquid film thickness was ±10% or more, and only a liquid filminappropriate for practical use can be obtained.

It is apparent from the above-described studies that the distance hbetween the discharge port of the solution discharge nozzle and thesubstrate is preferably set as follows:2 [mm]≦h<5×10⁻⁵ qγ  (4)

The apparatus of FIG. 1 was used to adjust the distance h in a range of0.5 mm to 10 mm, an 8-inch wafer was coated with the resist solution toform the liquid film, and further the solvent in the solution wasdried/removed to form a solid film. Here, the solvent was removed, afterthe substrate with the liquid film formed thereon was exposed to anatmosphere of ethyl lactate as that of the solvent included in theliquid film and the liquid film was leveled. The substrate on which theliquid film was leveled was moved into a pressure reduction chamber, thepressure inside the pressure reduction chamber was reduced, and thesolvent was removed in the state of the pressure held in the vicinity ofa saturated vapor pressure of ethyl lactate. Furthermore, after thepressure was returned to normal, the substrate was conveyed out of thepressure reduction chamber, heated at 140° C. on a hot plate, and anyremaining solvent present in the film was removed. Note that thesubstrate may directly be heated by a baker, instead of using a hotplate in times of the solvent in the solution was dried/removed exposingthe substrate to reduced pressure. Moreover, the substrate may berotated, and dried by air.

The discharge speed from the discharge port of the solution dischargenozzle was set to 4.77 m/sec and doubled to 9.54 m/sec, and the liquidfilm was formed. Note that the movement speed of the solution nozzle wasset to 1 m/sec with the discharge speed of 4.77 m/sec and the movementspeed of the solution discharge nozzle was set to 2 m/sec with thedischarge speed of 0.54 m/sec so as to obtain the same liquid filmthickness at both the discharge speeds. Moreover, when the dischargespeed was 4.77 m/s, an upper-limit distance Hp was 7.16 mm. When thedischarge speed was 9.54 m/s, the upper-limit distance Hp was 14.3 mm

With respect to the formed solid film, a relation of a film thicknessdistribution (range %) in a wafer surface to the distance h between thedischarge nozzle of the solution discharge nozzle and the substrate isshown in FIG. 7. Moreover, a relation of the number of particles perwafer with respect to the discharge port-substrate distance h is shownin FIG. 8.

As seen from FIG. 7, with the resist solution, for the film thicknessuniformity, when the discharge port-substrate distance h was set to 3 mmor more, it was possible to obtain a stabilized value. Note that to forminterlayer films or to apply a solution including a low-dielectricmaterial, a range of film thickness uniformity of about 5% issufficient, and therefore the distance is preferably 2 mm or more.

For the result of particles of FIG. 8, a satisfactory result wasobtained in a range which satisfied the equation (4) with respect toeach discharge speed, and the result was also obtained that the numberof defects increased in another region. The reason why there are manydefects with h≦2 mm is that the distance between the nozzle andsubstrate is short, therefore the solution sputtered on the substratestuck to the nozzle, and this discharged onto the substrate, generatingdefects, or that the solution contacting the nozzle was scattered as amist, and stuck to the substrate, generating defects. One reason why theparticles increase at an upper-limit distance Hp or more distance isthought to be that a part of the solution discharged as described aboveforms micro liquid drops, providing a mist which generates theparticles. Due to this, the distance h between the discharge port of thesolution discharge nozzle and the substrate may be set in the rangewhich satisfies the condition of the equation (4).

It is possible to automatically set the distance h between the dischargeport of the solution discharge nozzle and the substrate in the coatingapparatus. In this case, the coating apparatus is constituted so thatthe surface tension γ (N/m) of the solution to be applied can beregistered. On an apparatus side, an appropriate distance h may becalculated by the equation (4) in accordance with the registered surfacetension γ and discharge speed q (M/sec) at this time. The distancebetween the discharge port of the solution discharge nozzle and thesubstrate is adjusted so as to reach the obtained appropriate distance hbefore the solution is supplied to the substrate. For the adjustment ofthe distance, the substrate may be moved upwards/downwards, a solutiondischarge nozzle driving system may be moved, or both may be moved.

The discharge speed q (m/sec) may directly be inputted by an operator,or is preferably automatically calculated in the coating apparatus. FIG.9 is an explanatory view of a method of calculating the discharge speedq of the solution, when relative movement of the solution dischargenozzle and substrate is constituted of a combination of linear movementof the column direction of the solution discharge nozzle passing alongthe substrate from one end of the substrate through to the other end ofthe substrate with movement of the row direction outside the substrate.As shown in FIG. 9, assuming that for a discharge speed q (m/sec) of asolution 82, a desired average liquid film thickness of a liquid film 83is df, a movement pitch of the row direction of the nozzle is p (=widthof unit liquid film), a radius of a discharge hole 81 of the solutiondischarge nozzle is r, and the speed of the linear movement of thecolumn direction of the solution discharge nozzle passing along thesubstrate from one end of the substrate to the other end of thesubstrate is v (m/s), the following relation is established from arelation in which a liquid amount of a coat region is equal to an amountof discharged liquid:d _(f) [m]×p [m]×v [m/s]=π(r [m])² q [m/s]  (5)When this relation is organized with respect to the discharge speed q ofthe solution 82, the following relation is obtained:q=d _(f) ×p×v/πr ²  (6)Note that the average liquid film thickness can easily be obtained usinga desired average film thickness of the solid film, solid contentconcentration in the solution, and density of solid and liquid films bymeans described in a conventional chemistry textbook.

For the relative movement of the solution discharge nozzle andsubstrate, even when the solution discharge nozzle moves in a spiralform toward an outer periphery from the center of the substrate orinwards from the outer periphery, the following relation is established:d _(f) [m]×p [m]×v [m/s]≅π(r [m])² q [m/s]  (7)wherein the desired average liquid film thickness is assumed to bed_(f), movement pitch of the discharge nozzle of the diameter directionper one rotation of the substrate in an outermost periphery is p, thedischarge hole radius of the solution discharge nozzle is r, and arelative linear velocity of the solution discharge nozzle with respectto the substrate in the outermost periphery is v.

When this equation is organized with respect to q, the followingrelation can be obtained:q=d _(f) ×p×v/πr ²  (8)

Note that the distance h may be in any region within the range obtainedby the equation (4). To simply obtain the distance in the apparatus, thedistance may also be determined as an intermediate value between theupper and lower limits. Moreover, when a solution cut-off function suchas a shield plate is disposed between the solution discharge nozzle andsubstrate, and the position of the solution cut-off function is apartfrom the discharge port of the solution discharge nozzle by 2 mm ormore, it is necessary to regard the position of solution dischargenozzle as the lower limit and set h.

Moreover, when the solution is supplied onto the substrate by thecombination of the movement of the column direction of the nozzle withthe movement of the row direction, the method described in the presentembodiment can be applied not only to a circular substrate but also to arectangular substrate.

SECOND EMBODIMENT

For a second embodiment, in the coating method using the coatingapparatus shown in FIG. 1, supply amount correction will be describedwith respect to a liquid line discharged, supplied, and formed on thesubstrate while linearly moving the nozzle.

The liquid film was prepared under the same conditions as that of thefirst embodiment, and further the solvent was dried/removed to form thesolid film. The solvent in the liquid film was dried in the same manneras in the first embodiment.

Prior-art control of the movement and discharge speeds of the solutiondischarge nozzle was executed along a time axis under the control ofPID. This control is fed back so that the movement and discharge speedsof the solution discharge nozzle indicate the set values. Moreover, whenone line is drawn by the discharged solution, the control was fed backwith respect to a front part of the solution discharge nozzle in aproceeding direction. However, a real uniform film cannot be obtainedonly with this control method. Preferably a control is executed to makea correction between adjacent lines.

For example, in the related art, when the PID control is executed withrespect to deviations of the discharge and movement speeds, as shown inFIG. 10, the film thickness of the liquid film formed on the substratewith respect to the discharge position of the solution changes. Notethat the liquid film thickness in FIG. 10 is exchanged from a supplyamount to the discharge position and obtained in consideration of thespread of the solution discharged onto the substrate.

When the supply amounts of the solution to the discharge positions arecompared in the regions disposed adjacent to each other, the supplyamount changes substantially in the same track. As a result, as shown bya broken line of FIG. 12, there is a problem that the film thicknessvariation is generated along the column direction of the solutiondischarge nozzle in the finally formed solid film.

To solve the problem, the method of the present embodiment comprises:storing a deviation amount of the supply amount; and obtaining thedeviation of the supply amount with respect to the discharge position,when one line is drawn with the discharged solution in the columndirection. The liquid film thickness (corresponding to the supplyamount) with respect to the discharge position at this time is shown bya solid line in FIG. 11. Note that the liquid film thickness in FIG. 11is exchanged from the supply amount to the discharge position andobtained in consideration of the spread of the solution discharged ontothe solution. Also noted that the deviation amount of the supply amountis generated, for example, by deviation of the discharge speed from thesolution discharge nozzle, and deviation of the movement speed of thesolution discharge nozzle.

Moreover, a discharge amount in an arbitrary position in a region(second column) disposed adjacent to a track (first column) in which thedeviation amount of the supply amount is obtained is controlled so as tocompensate for the deviation amount of the supply amount obtained in theadjacent discharge position. The supply amount of the solution iscontrolled by controlling at least one of the discharge speed and themovement speed of the solution discharge nozzle. In the adjacentdischarge region, a fluctuation of the liquid film thickness is shown bya broken line in FIG. 11.

As a result, since the directions of fluctuations of the liquid filmthickness are reverse to each other in the adjacent lines, thefluctuations are offset and the uniform liquid film thickness can beobtained. As a result, the film thickness of the solid film obtainedafter removing the solvent in the liquid film is flat, irrespective ofthe discharge position, as shown by a solid line in FIG. 12.

Note that the deviation amount of the discharge speed can be measured,for example, by monitoring the change of discharge pressure. Moreover,the deviation amount of the movement speed of the solution dischargenozzle can be obtained as a differential value with respect to time,when position information of the nozzle is obtained with a laserinterferometer.

Note that the present embodiment can of course be applied to a methodcomprising: rotating the substrate; moving the solution discharge nozzlein the diameter direction of the substrate; and discharging the solutionin a spiral form onto the substrate to form the liquid film. In thiscase, the deviation of the discharge speed of the solution from thesolution discharge nozzle, the deviation of the movement speed of thesolution discharge nozzle, and the deviation of the rotation speed ofthe substrate are measured to obtain the deviation of the supply amount.Moreover, to supply the solution into a first position of the substratefrom the solution discharge nozzle, the supply amount of the solutionsupplied to the first position is controlled so as to compensate for thedeviation amount in the second position in which the solution hasalready been discharged and which is disposed adjacent to the firstdischarge position in the diameter direction of the substrate. Thesolution supply amount is controlled by controlling at least one of thedischarge speed of the solution from the solution discharge nozzle,movement speed of the solution discharge nozzle, and rotation speed ofthe substrate.

Moreover, the substrate may also be dried using only a baker.Furthermore, the substrate may be rotated, and air blown one's it to dryit.

Furthermore, to supply the solution onto the substrate by thecombination of the movement of the column direction of the nozzle withthe movement of the row direction, the method described in the presentembodiment can be applied not only to a circular substrate but also to arectangular substrate.

THIRD EMBODIMENT

FIGS. 13A, 13B are diagrams showing a schematic constitution of a liquidfilm forming apparatus according to a third embodiment of the presentinvention. FIG. 13A is a side view of the apparatus, and FIG. 13B is aplan view of the apparatus.

As shown in FIGS. 13A, 13B, a substrate 120 is horizontally disposed ona substrate driving system 121. Above the substrate 120, a solutiondischarge nozzle 122, and a nozzle driving system 123 forreciprocating/moving the nozzle 122 are disposed above the substrate120. The solution discharge nozzle 122 is controlled so as to dischargethe solution and to reciprocate/move leftwards/rightwards along a sheetsurface (this direction is regarded as the column direction) above thesubstrate 120, and shield plates 124 a, 124 b disposed in a spacebetween the substrate 120 and solution discharge nozzle 122 by thenozzle driving system 123.

Every time the solution discharge nozzle 122 moves in one directionabove the substrate 120, the substrate 120 is controlled so as to move apredetermined pitch in a predetermined row direction backwards orforwards by the substrate driving system 121. As shown in FIG. 14, whenthis operation is repeated, the track of the discharge position of thesolution discharged onto the substrate 120 forms a line shown by anumeral number 131. The track 131 of the discharge position is linear,and the linearly supplied solution spreads on a basis of a reachposition on the substrate by fluidity of the solution, and is connectedto the adjacent liquid line to finally form one liquid film. For this,viscosity of the solution, and movement pitch of the row direction aredetermined beforehand.

The shield plates 124 a, 124 b disposed in the space between thesubstrate 120 and solution discharge nozzle 122 move along an outer edgeof the substrate 120 by a cut-off mechanism driving system 126, and arms125 a, 125 b, stop discharge of solution 127 from the solution dischargenozzle 122, thus prevent the solution from reaching the substrate 120.

In a related-art method for coating a circular substrate, the columndirection positions of the shield plates 124, that is, a coating startside cut-off position L_(s) and coating end side cut-off position L_(e)are determined as follows, assuming that a substrate origin is 0 andusing a radius r of the substrate, edge cut width (distance between asubstrate edge and liquid film edge forming position) d, and distance Xfrom the liquid line of the solution from the solution discharge nozzle:|L _(s) |=|L _(e)|=((r−d)² −x ²)^(0.5)  (9)

FIGS. 15A, 15B schematically show the reach position of the solutionactually cut off at this time on the substrate. The solution dischargenozzle 122 moves forwards in an arrow direction at v (m/sec). On theother hand, it is assumed that the discharge speed of the solution 127from the nozzle 122 is q (m/sec). Further, it is assumed that thedistance between the shield plate and substrate (height of cut off ofthe solution on the basis of the substrate) is z (m). To usually applythe diluted solution with this coating apparatus, the discharge speed isabout q=5 to 15 m/sec, and distance is about z=0.001 to 0.005 m. Since adistance z between the discharge port of the solution discharge nozzle122 and the substrate 120 is very small as compared with the dischargespeed, the speed change in the discharge distance can be assumed to besubstantially 0. Errors ΔL₁ and ΔL₂ of the solution reach position ontothe substrate from a cut-off position under this condition can berepresented as follows:|ΔL ₁ |=|ΔL ₂ |=vz/q  (10)

When the movement speed of the solution discharge nozzle is v=1 m/sec,the discharge speed is q=5 m/s, and z=0.003 m, the errors are asfollows:|ΔL ₁ |=|ΔL ₂|=0.6 mm  (11)

Therefore, a generated difference of the edges of the solutions drawnadjacent to each other is about 1.2 mm with the rectangular substrate.To coat the circular substrate, a coat film profile in which the edgesare further disordered is obtained as shown in FIG. 16.

On the other hand, in the present embodiment, when a liquid lineproceeding direction is set to +, fine adjustment is made so as to shiftcut-off positions on supply start and end sides from the positiondetermined by the equation (9) by −vz/q. Thereby, the liquid film can beformed along a substrate contour shown in FIG. 17.

The solution supplied onto the substrate spreads by fluidity and forms aliquid film. At this stage, the edge of the liquid film can have an edgeprofile along the substrate.

The liquid film prepared with the edge profile along the substrate maybe rotated centering on the substrate, so that the liquid film can beleveled. Moreover, when the substrate is rotated and dried in a dryingstep, the solvent can be evaporated from the liquid film in a outerperipheral portion with good balance, and the film thickness variationgenerated by evaporation can be minimized.

The above-described effect is an effect obtained by forming an edgeportion along the substrate. When the substrate is rotated, acentrifugal force applied to the liquid film can equally be scattered inthe liquid film edge as shown in FIG. 18A, and the effect can beobtained. With a zigzag edge as in the related art, as shown in FIG.18B, the centrifugal force is concentrated in a projecting portion ofthe liquid film, and therefore there is a problem that the liquid flowstoward the outside of the substrate from this portion.

Note that a method of removing the solvent from the liquid film maycomprise: exposing the substrate on which the liquid film is formed toan atmosphere of ethyl lactate as that of the solvent included in theliquid film to level the liquid film; subsequently moving the substrateinto the pressure reduction chamber; reducing the pressure; removing thesolvent in the state held at the pressure in the vicinity of thesaturated vapor pressure of ethyl lactate; further returning thepressure to normal pressure and thereafter conveying the substrate outof the pressure reduction chamber; and heating the substrate at 140° C.on a hot plate to remove the solvent form the film. Alternatively, thesolvent may also be removed by directly heating the substrate, withoutexposing it to reduced pressure.

In the present embodiment, the correction with respect to the circularsubstrate has been described, but when a similar correction is made inthe coating of a mask for exposure of a rectangular substrate, such as aliquid crystal substrate, it is possible to form a liquid film having anedge along the substrate edge. Also for a rectangular substrate, whenthe proceeding direction of the solution discharge nozzle is set to +,the cut-off positions on the supply start and end sides may be matchedwith positions obtained by shifting the cut-off position by the shieldplate from the liquid film edge forming position formed in the edge ofthe rectangular substrate at a constant interval by −vz/q.

Moreover, in addition to the shield plates shown in FIGS. 13A, 13B, thefollowing cut-off mechanisms for preventing the solution from reachingthe substrate are considered:

(i) a mechanism for spraying gas to change the track of the liquid, andcollecting the solution in a recovery portion disposed in an oppositeposition; and

(ii) a mechanism for sucking the discharged solution to change thetrack, and collecting the liquid into a liquid recovery portion.

One example of a liquid film forming apparatus including a mechanismdifferent from a gas cut-off mechanism shown in FIGS. 13A, 13B is shownin FIGS. 19A, 19B. As shown in FIGS. 19A, 19B, the present apparatusincludes gas emission portions 184 a, 184 b for emitting gas to thedischarged solution, and solution suction portions 185 a, 185 b forrecovering the solution by suction, and a system including both thecut-off mechanisms (i) and (ii) is used. Note that the shield plates 124a, 124 b are disposed to prevent the solution which cannot be cut off bythe gas emission portions 184 a, 184 b and solution suction portions 185a, 185 b from discharging onto the substrate.

For the driving method, the same control as that of the apparatus shownin FIGS. 13A, 13B is executed, but the distance z is treated as adistance between the gas emission portions 184 a, 184 b for spraying thegas to cut off the solution and the substrate 120.

Moreover, to supply the solution onto the substrate by the combinationof the movement of the column direction of the nozzle with the movementin the row direction, the method described in the present embodiment canbe applied not only to a circular substrate but also to a rectangularsubstrate.

FOURTH EMBODIMENT

FIGS. 20A, 20B, 21A, 21B are explanatory views of problems according toa fourth embodiment of the present invention, and are explanatory viewsof problems generated when the solution discharge nozzle turns backalong the contour of the circular substrate to form the coat film asshown in FIG. 1.

The solution linearly discharged onto the substrate from the solutiondischarge nozzle is regarded as the liquid line. Moreover, when theadjacent liquid lines stick to each other to form the liquid film, aportion formed by one liquid line is regarded as a unit liquid film.

FIGS. 20A, 20B schematically show a spread state of the liquid lineapplied in a first column at a coating time of a second column, andboundary of the unit liquid film in the finally obtained liquid film ina coating start/end portion at a time of preparation of the liquid filmusing the coating apparatus of FIG. 1. FIGS. 21A, 21B schematically showthe spread state of the liquid line applied in the first column at thecoating time of the second column, and boundary of the unit coat film inthe finally obtained liquid film in the vicinity of a substrate center.

In the coating start and end portions, the nozzle movement distance inthe column direction is short. A time from when the coating of the firstcolumn ends and the solution supply to the substrate is temporarilydiscontinued until the coating of the second column starts and thesolution supply to the substrate is restarted (column direction coatingtime interval) is short as compared with the coating of the substratecenter portion having substantially the same diameter as that of thesubstrate. This time difference gives a difference to the spread of thesolution line of the first column in applying the solution line of thesecond column.

As shown in FIG. 20A, in the vicinity of the coating start and end, thespread of a liquid line 192 of the first column at the coating time ofthe second column is insufficient. Therefore, as shown in FIG. 20B, aboundary B₁ of unit liquid films 193, 194 is determined on a dischargeposition P₁₂ side of the second column slightly from a center line C₁ ofa discharge position P₁₁ of the first column and discharge position P₁₂of the second column. In FIG. 20B, an interval between the center lineC₁ and position P₁₂ is set to SL1.

However, in the vicinity of the center, as shown in FIG. 21A, since thecolumn direction coating time interval is large, a liquid line 195 ofthe first column considerably spreads at the coating time of the secondcolumn. Therefore, as shown in FIG. 21B, a boundary B₂ of unit liquidfilms 196, 197 is determined further on the discharge position P₁₂ sideof the second column as compared with the vicinity of the coating startand end. In FIG. 21B, an interval between the center line C₂ andposition P₂₂ is set to SL2 (SL2>SL1).

Such difference of the boundary position of the unit liquid film is acause of deterioration of film thickness uniformity. Since the boundaryof the unit liquid film shifts toward a start point side from the centerin the coating start and end portions, a finally obtained amount ofsolid content value apparently moves on the start point side. Therefore,a problem occurs that the solid film is thick on the coating start sideand thin on the end side. In FIG. 22, plotted triangular marks indicatea relative film thickness with respect to the film thickness of thesubstrate center observed in related-art coating.

When the solution supply amount proportional to an inverse number of therelative film thickness is given to the corresponding column based onthe relative film thickness plotted by the triangular marks of FIG. 22,the film thickness uniformity in the row direction can be enhanced. Thesolution supply amount is adjusted by setting the discharge speed fromthe solution discharge nozzle to a value obtained by multiplying therelated-art discharge speed by the inverse number of the relative filmthickness obtained in the related-art coating method as a coefficient.Results of the relative film thickness obtained by the method of thepresent embodiment are shown by circular marks of FIG. 22. A uniformfilm thickness can be obtained in the whole row direction of thesubstrate.

The present embodiment is characterized in that the solution supplyamount to the substrate in the coating start vicinity is set to besmaller than in the center portion, and that the solution supply amountto the substrate in the coating end vicinity is set to be larger than inthe center portion. Therefore, the effects of the present embodiment canalso be achieved by the following control.

(1) The discharge speed from the solution discharge nozzle is changed inproportion to the inverse number of the relative film thickness. Notethat the same value as that in the related art is set for otherconditions such as the column-direction movement speed and row-directionmovement pitch of the solution discharge nozzle.

As shown in FIG. 22, the solid film is thick on the liquid film formingstart side, and thin on the liquid film forming end side. Therefore, thedischarge speed in moving the nozzle in the column direction is set tobe smaller than the discharge speed of the middle position of thesubstrate in the vicinity of the liquid film forming start position, andset to be larger than the discharge speed of the middle position of thesubstrate in the vicinity of the liquid film forming end position.

(2) The row-direction movement pitch of the solution discharge nozzle ischanged in proportion to the row-direction relative film thickness. Notethat the same value as that in the related art is set the for otherconditions such as the column-direction movement speed and dischargespeed of the solution discharge nozzle.

As shown in FIG. 22, the solid film is thick on the liquid film formingstart side, and is thin on the liquid film forming end side. Therefore,the row-direction movement distance in moving the nozzle in the rowdirection is set to be larger than the row-direction movement distanceof the middle position of the substrate in the vicinity of the liquidfilm forming start position, and set to be smaller than therow-direction movement distance of the middle position of the substratein the vicinity of the liquid film forming end position.

(3) The movement of the solution discharge nozzle in a state in whichthe solution is not supplied to the substrate is controlled to adjusttime. Preferably, an adjustment speed is adjusted, when the solutiondischarge nozzle moves in the row direction. Alternatively, theadjustment speed at the column-direction movement time of the nozzle isadjusted. Moreover, the adjustment speed in the row andcolumn-directions movement time may also be controlled. To decrease thetime interval, the adjustment speed may be increased. To lengthen thetime interval, the adjustment speed may be decreased. Note that theadjustment of the adjustment speed also comprises: temporarily stoppingthe movement of the nozzle.

In the present embodiment, the coating condition is set on the basis ofthe film thickness distribution of the film coated in the related-artmethod, but this is not limited. The setting method comprises:discharging the solution through the nozzle; supplying one coating lineonto the substrate; observing the spread of the line in the rowdirection by a CCD camera or video; and obtaining a speed of spread ofthe liquid line. On the other hand, a column-direction coating timeinterval generated in drawing the line with the coating apparatus ismeasured or obtained from specifications by desk calculation work. Theabove-described spread amount and column-direction coating time intervalare obtained. In this case, the condition is easily determined by themethod (3). Moreover, with the adjustment in the method (1), thedischarge speed in coating each column may be obtained. With theadjustment in the method (2), the movement pitch of the row directionmay be determined.

The present invention is not limited to the above-described embodiments,and can variously be modified within a range of the scope in animplementation stage. For example, the liquid film forming methoddescribed above in the respective embodiments can be applied to asemiconductor process including the coating of a reflection preventiveagent, or resist agent for use in a lithography process, and the coatingof low or high dielectric material, and to any other film formingprocess including an ornamental process such as plating.

FIFTH EMBODIMENT

In a fifth embodiment, a semiconductor substrate having a diameter(f)=200 mm was used, and a photoresist solution for chemicalamplification was used as one concrete example in the solution. Here, itis assumed that the photoresist solution for chemical amplificationincludes a solid content of 3.0%. This solid content indicates a ratioof the solid content included in the solution of the photoresist. Thesolid content remains as a solid film after a drying and bakingtreatment. Moreover, it is assumed that a film to be processed (e.g.,insulating film) is formed on a semiconductor substrate beforehand by aknown method.

First, the substrate is introduced into a scan coating treatment unit,and laid and fixed on a stage. Thereafter, while a solution A isdischarged through a nozzle for solution supply, the nozzle isreciprocated/moved along a column-direction at a speed of 1 m/sec by anozzle driving unit. Moreover, the stage is simultaneously moved in anrow-direction at a pitch interval of 0.6 mm by a stage driving unit.Here, the whole surface (=plane) of the substrate is coated with thesolution A, and the liquid film is formed with a film thickness of about10 μm. At this time, the concave/convex portion was formed in the liquidfilm on the substrate at a flatness of about 10 μm±10%. Note that thesame degree of concave/convex portion is observed in the liquid on thesubstrate even with the use of meniscus coating using the capillaryphenomenon.

Subsequently, a leveling treatment is performed to flat the liquid filmon the substrate. Usually after the liquid film is formed on thesubstrate, the surface of the liquid film is not completely smooth asdescribed above, and the concave/convex portion exists because of thefluctuation of the discharge amount in discharging the solution. Tosolve the problem, if necessary, first the leveling treatment isperformed to flat the surface of the liquid film. Thereafter, the dryingtreatment is carried out to vaporize the solvent of the photoresistsolution constituting the liquid film, and a photoresist coat filmincluding the solid content is formed.

In the present embodiment, in one example, a leveling/drying treatmentapparatus 200 shown in FIG. 23 is used to subject the liquid film 16 tothe leveling and drying treatment, and a series of treatments isperformed so as to form a photoresist film which has a uniform thicknessand whose surface is flatted over the whole surface of the substrate 11.

The leveling/drying treatment apparatus 200 is constituted by integrallyincluding a function required for the leveling and drying treatment, sothat the treatment is carried out in the same chamber. The constitutionand function of the leveling/drying treatment apparatus 200 will bedescribed hereinafter with reference to FIG. 23.

The leveling/drying treatment apparatus 200 includes a chamber 201 inwhich the substrate 11 (e.g., semiconductor substrate having a diameter(f) 200 nm) is contained, an gas control unit 202, and an exhaust unit203 which exhausts the atmosphere in the chamber 201. The gas controlunit 202 mixes inactive gas for dilution (e.g., N₂ gas) and solvent gasat a predetermined ratio, and supplies gas including the solvent at adesired concentration into the chamber 201. This solvent is the same asthat included in the resist solution.

Here, a stage 205 on which the substrate 11 is laid and fixed isdisposed in the chamber 201. A temperature control plate 206 foradjusting temperature distribution of the substrate 11 is disposed in aposition under the stage 205.

The temperature control plate 206 can independently control thetemperature of a plurality of regions of the substrate 11. FIG. 24 showsa constitution of the temperature control plate according to the presentembodiment. As shown in FIG. 24, the temperature control plate 206includes a middle plate 206 a and peripheral edge plate 206 b. Themiddle plate 206 a and peripheral edge plate 206 b independently controlthe temperature of the regions of the peripheral edge portion and middleportion of the substrate 11.

Moreover, the gas control unit 202 includes valves for gas supply V₁ toV₃. The flow rate of inactive gas for dilution (e.g., N₂ gas) iscontrolled by adjustment of opening of the valve V₁. Moreover, the flowrate is controlled by the adjustment of the flow rate of solvent gas andopening of the valve V₂. When the openings of the valves V₁ and V₂ areadjusted, two gases are mixed at a predetermined density. The opening ofthe valve V₃ is adjusted to control the supply amount of mixed gas intothe chamber 201.

The exhaust unit 203 has a vacuum pump and valve V₄. The valve V₄ isinserted into a pipe which connects the chamber 201 to the vacuum pump.When the opening of the valve V₄ is adjusted, air current amount andpressure of the atmosphere in the chamber 201 are adjusted. Furthermore,the leveling/drying treatment apparatus 200 includes an optical systemfor film thickness measurement 207 to measure the film thickness of theliquid film 16 in each treatment step. The optical system for filmthickness measurement 207 mainly includes a light irradiation portion208 and light receiving portion 209. The light irradiation portion 208is constituted of a light source which emits a light having a wavelengthin a visible region. The light receiving portion 209 is constituted of aCCD camera. Moreover, a plurality of sets of light sources 208 and lightreceiving portions 209 are disposed so as to measure the film thicknessof the liquid film 16 in a plurality of positions on the substrate 11.

Additionally, the leveling/drying treatment apparatus 200 includes ananalysis unit 210. The analysis unit 210 is connected to the gas controlunit 202, temperature control plate 206, and optical system for filmthickness measurement 207.

The light source 208 irradiates the liquid film 16 with visible light.The light receiving portion 209 receives the reflected light andmeasures light intensity. The analysis unit 210 calculates the filmthickness of the liquid film 16 from the intensity of the reflectedlight. Moreover, the analysis unit 210 controls the concentration of thesolvent in the gas supplied into the chamber 201, pressure in thechamber 201, temperature of the substrate 11, and exhaust in the chamber201 in accordance with the calculated film thickness of the liquid film16.

The leveling/drying treatment apparatus 200 constituted as describedabove is used to first perform the leveling treatment so that the filmthickness of the liquid film 16 is uniform and the surface of the filmis flatted in the whole surface of the substrate 11.

Conditions such as the temperature of the substrate at a levelingtreatment time, flow rate of the air current in the treatment apparatus,exhaust, concentration of the solvent in the gas, and pressure arechanged, and the substrate for test is used to perform the levelingtreatment. During the leveling treatment, a film thickness difference ofthe center and peripheral edge regions of the substrate are observed. Acondition on which the difference of the film thickness measured in eachregion is small is set to an initial condition of the levelingtreatment. The film thickness difference is observed by irradiating eachregion with light and counting the number of interference fringes of thereflected light. When the number of interference fringes is small, thefilm thickness difference is small.

The procedure of the leveling treatment will concretely be describedwith reference to FIGS. 25, and 26A to 26C. FIG. 26A is a diagramshowing a change of the film thickness of the liquid film in eachposition on the substrate with time in the leveling treatment accordingto the fifth embodiment, FIG. 26B is a diagram showing a change ofsolvent concentration in gas supplied into the chamber with time in theleveling treatment according to the fifth embodiment, and FIG. 26C is adiagram showing a change of temperature of middle and peripheral edgeplates in the leveling treatment according to the fifth embodiment.

First, the substrate 11 is conveyed into the chamber 201 of theleveling/drying treatment apparatus 200, and laid and fixed onto thestage 205. At this time, temperature T_(c) of the middle plate 206 adisposed in the stage 205, and temperature T_(r) of the peripheral edgeplate 206 b are set around room temperature (e.g., 23° C.).

Thereafter, the leveling treatment is started to flat the surface of theliquid film 16. The openings of the valves for gas supply V₁ to V₃ ofthe gas control unit 202 are adjusted, and a mixture gas is generated bymixing the solvent gas and gas for dilution in a predeterminedconcentration. The mixture gas is supplied into the chamber 201, and theatmosphere including the solvent is formed in the chamber 201. In thepresent embodiment, the concentration of the solvent in the mixture gasat the start time of the leveling treatment is 100%.

The same solvent as that constituting the liquid film 16, or a similarsolvent is used in the solvent gas. When the liquid film 16 is exposedto the atmosphere including the solvent, the fluidity inside the liquidfilm 16 is promoted, and the surface tension can be used to smooth thesurface.

In the present embodiment, in the process of the leveling treatment, thefilm thickness of the liquid film 16 is measured, a necessary parameteris selected from parameters relating to the treatment in accordance withmeasurement result, and the value of the parameter is controlled. Atthis time, the value of the selected parameter is controlled. By thiscontrol, during the leveling treatment, the film thickness difference ofthe liquid film 16 is controlled over the whole surface of the substrate11. Here, in one example, as the parameter, the concentration of thesolvent in the chamber 201, and temperature distribution of thesubstrate 11 are selected, and the values of these parameters arecontrolled.

In this case, in the present embodiment, during the leveling treatment,the optical system for film thickness measurement 207 and analysis unit210 are used to measure the film thickness of the liquid film 16 in aplurality of positions in the peripheral edge from the middle portion ofthe substrate 11. At this time, the film thickness of the liquid film 16is measured in a plurality of points P₁, P₂, P₃ on the substrate shownin FIG. 25.

FIG. 25 shows a sectional view of the substrate 11 and liquid film 16.Here, the point P₁ is an arbitrary position on a middle portion R_(c) ofthe substrate 11, point P₃ is an arbitrary position on a peripheral edgeR_(r) of the substrate 11, and P₂ is an arbitrary position between P₁and P₃ in the substrate 11.

Note that in the present embodiment, the peripheral edge R_(r) indicatesa region in a width corresponding to about 5% of a substrate diameterfrom the edge (=endmost portion) of the substrate. Therefore, when thediameter (f) of the substrate is 200 mm, the peripheral edge indicatesthe region in a width of 10 mm from the edge (=endmost portion).

In the process of the leveling treatment, in the leveling/dryingtreatment apparatus 200, the optical system for film thicknessmeasurement 207 is used to measure the film thickness of the liquid film16 in the respective points P₁, P₂, P₃. Moreover, in order to inhibitthe film thickness in each point from increasing/decreasing, theanalysis unit 210 sends an instruction to the gas control unit 202 andtemperature control plate 206, and the concentration of the solvent inthe chamber 201 and temperature distribution of the substrate 11 arecontrolled.

The leveling treatment will concretely be described hereinafter withreference to FIGS. 26A to 26C.

As shown in FIG. 26A, immediately after the leveling treatment isstarted, the film thickness of the liquid film 16 in the respectivepoints P₁, P₂, P₃ on the substrate 11 largely deviate. Thereafter, onthe basis of the preset film thickness (e.g., 10 μm), in the respectivepoints P₁, P₂, P₃ on the substrate 11, the concentration of the solventin the chamber 201 and temperature distribution of the substrate 11 arecontrolled so that the film thickness of the liquid film 16 is within agiven range.

Concretely, as shown in FIG. 26B, the concentration of the solvent inthe mixture gas supplied into the chamber 201 is 100% immediately afterthe start of the leveling treatment. Thereafter, the concentration ofthe solvent in the mixture gas is gradually reduced to 60%. Here, thesurface of the liquid film 16 is flatted, and the concentration of thesolvent in the chamber 201 is gradually decreased so that the filmthickness difference of the liquid film 16 is within a substantiallyconstant range in the respective points P₁, P₂, P₃ on the substrate 11.

Moreover, while the concentration of the solvent in the atmosphere iscontrolled, the temperature of the temperature control plate 206 issimultaneously controlled independently in the middle and peripheraledge portions of the substrate 11. Concretely, when the substrate 11 islaid on the stage 205, the whole temperature control plate 206 is set toa substantially constant temperature. Thereafter, in the process of theleveling treatment, the temperature is controlled independently in thepositions of the middle portion corresponding to the point P₁ and theperipheral edge corresponding to the point P₃.

Here, in one example, first the temperature T_(c) of the middle plate206 a and temperature T_(r) of the peripheral edge plate 206 b are setat temperature of about 23° C., before the substrate 11 is laid on thestage 205. Thereafter, as shown in FIG. 26C, the temperature T_(c) ofthe middle plate 206 a is kept at 23° C. The temperature T_(r) of theperipheral edge plate 206 b is lowered to about 15° C. During theleveling treatment, the temperature T_(c) of the middle plate 206 a iscontrolled to be kept at 15° C. During the leveling treatment, thetemperature of the peripheral edge R_(r) of the substrate 11 is set tobe lower than that of the middle portion R_(c). By this temperaturedistribution, the solid content is inhibited from flowing in a directionof the middle portion R_(c) from the peripheral edge R_(r), and the filmthickness distribution is within a constant range.

Thereafter, when the film thickness of the liquid film 16 in therespective points P₁, P₂, P₃ is within the given range on the basis ofthe preset film thickness, the leveling treatment ends. The levelingtreatment ends, when all the valves V₁ to V₃ of the gas supply systemare closed and the supply of the gas into the chamber 201 is stopped.

Note that in one example the film thickness of the liquid film 16 in therespective points P₁, P₂, P₃ is within a range of about ±0.5% on thebasis of 10 μm and at this time the leveling treatment of the presentembodiment ends.

Subsequently, the drying treatment is performed so as to vaporize thesolvent of the liquid film 16 in the state in which the substrate 11 islaid on the stage 205 in the chamber 201. This drying treatmentcomprises: vaporizing the solvent in the liquid film 16; and leaving thesolid content in the liquid film 16 on the substrate 11 to form thesolid film on the substrate. As one example, the present embodimentcomprises: vaporizing the photoresist solution by a pressure reductiontreatment; and forming the photoresist film having a film thickness ofabout 400 nm as the solid film. Here, after the supply of the mixturegas into the chamber 201 is stopped, first a vacuum pump 204 is used toexhaust the atmosphere in the chamber 201 at a predetermined rate.

For the respective conditions such as the temperature of the substrateat the drying treatment time, air current, concentration of the solventin the gas supplied into the chamber, and pressure, while a substratefor test is used to change the respective conditions beforehand, thefilm thickness is measured by reflected light measurement in a pluralityof points including at least the center of the substrate, coating startposition, and coating end position. Even in the process of the decreaseof the film thickness of the liquid film, a condition at a time ofreduction of the interference fringes of the reflected light may bedetermined from these results.

In the present embodiment, in the process of the drying treatment, thefilm thickness of the liquid film 16 is measured and monitored.Additionally, the necessary parameter is selected from the parametersrelating to the treatment, and the value of the parameter is controlled.At this time, while the value of the selected parameter is controlled,and the drying treatment is performed, the film thickness difference ofthe liquid film 16 is controlled to be within the predetermined rangeover the whole surface of the substrate 11, the solvent is vaporized,and finally the solid film having a thickness of 400 nm is formed. Here,in one example, the temperature distribution of the substrate 11 isselected as the parameter, and the value is controlled.

In this case, in the present embodiment, during the drying treatment,the optical system for film thickness measurement 207 and analysis unit210 are used to measure the film thickness of the liquid film in therespective points P₁ to P₃ in the same manner as in the levelingtreatment. At this time, the analysis unit 210 controls each parameterso that the difference of the film thickness in these points P₁ to P₃ iswithin the predetermined range. In the present embodiment, in oneexample, the value of the parameter is controlled so that the filmthickness of the points P₁ to P₃ is within a range of an average filmthickness value ±0.5%.

Here, the drying treatment will concretely be described with referenceto FIGS. 27A to 27C. FIG. 27A is a diagram showing the change of thefilm thickness of the liquid film in each position on the substrate withtime in the leveling and drying treatments according to the fifthembodiment, FIG. 27B is a diagram showing the change of pressure in thechamber with time in the leveling and drying treatments according to thefifth embodiment, and FIG. 27C is a diagram showing the change oftemperature of the middle and peripheral edge plates in the leveling anddrying treatments according to the fifth embodiment. Moreover, FIGS. 27Ato 27C show the states of the above-described leveling and dryingtreatments.

In the present embodiment, as shown in FIG. 27A, the difference of thefilm thickness is controlled to be within the given range, the dryingtreatment is carried out until the predetermined film thickness (e.g.,400 nm) is obtained, and the solvent in the liquid film 16 is vaporized.

Moreover, in the present embodiment, the drying treatment is performedin the reduced pressure state in the chamber 201. In order to vaporizethe solvent in the liquid film 16, the vacuum pump disposed in theexhaust unit 203 is used to exhaust the atmosphere in the chamber 201 tothe outside at −60 Torr/sec. Concretely, as shown in FIG. 27B, thepressure in the chamber 201 is kept at about 760 Torr during theleveling treatment. At the drying treatment time, the atmosphere in thechamber is exhausted at −60 Torr/sec, and pressure is lowered to andkept at about 2 Torr corresponding to the vapor pressure of the solvent.

At this time, in the process of the drying treatment, the temperature ofthe substrate 11 is controlled. A case in which the measured filmthickness of the point P₃ tends to be smaller than that of theperipheral edge will be described. Here, as shown in FIG. 27C, thetemperature T_(r) of the peripheral edge plate 206 b is graduallylowered to about 13° C. from 15° C. Thereafter, the temperature of theperipheral edge plate 206 b is kept at 13° C. On the other hand, thetemperature T_(c) of the middle plate is kept at about 23° C. (=roomtemperature) in the same manner as in the leveling treatment. During thedrying treatment, the temperature of the peripheral edge of thesubstrate 11 is set to be lower than that of the middle portion. Whenthe temperature distribution of the substrate 11 is controlled in thismanner, a vaporization speed of the solvent on the peripheral edgedischarges as compared with the middle portion, and it is possible toinhibit the solid content from moving into the middle portion from theperipheral edge.

When the measured film thickness of the point P₃ tends to be thickerthan that of the peripheral edge, the temperature of the peripheral edgeof the substrate 11 is set to be higher than that of the middle portion.When the temperature distribution of the substrate 11 is controlled inthis manner, the vaporization speed of the solvent on the middle portiondischarges as compared with that on the middle portion, and it ispossible to inhibit the solid content from moving into the peripheraledge from the middle portion.

In the present embodiment, the drying treatment ends at a time when thesolvent of the liquid film 16 is sufficiently vaporized and the filmthickness of the liquid film 16 reaches a predetermined film thickness(e.g., 400 nm) and does not change in the respective points P₁, P₂, P₃on the substrate 11.

Subsequently, the substrate 11 is conveyed out of the leveling/dryingtreatment apparatus 200, and introduced into a back treatment portion(not shown). Here, when a heating treatment is performed at 140° C. forabout 50 seconds, the film is stabilized.

As described above, the coat film of the photoresist with a thickness ofabout 400 nm (=film of the solid content included in the liquid film 16)is formed as the solid film. Here, the effect of the present embodimentwill be described in comparison to the related-art method with referenceto FIGS. 28A to 28C and 29A and 29B. FIG. 28A is a diagram showing thechange of the film thickness of the liquid film in each position on thesubstrate with time in the leveling and drying treatments according tothe fifth embodiment, FIG. 28B is a diagram showing the change of thefilm thickness of the liquid film in each position on the substrate withtime in the related-art leveling and drying treatments, and FIG. 28C isa diagram showing the change of the film thickness of the liquid film ineach position on the substrate with time in the related-art leveling anddrying treatments. FIGS. 29A, 29B are diagrams showing the effect of thefifth embodiment.

In the present embodiment, as shown in FIG. 28A, the film thickness ofthe liquid film is controlled to be within the given range as neededduring the leveling and drying treatments.

In the related-art method, without controlling the concentration of thesolvent in the chamber 201, and temperature distribution of thesubstrate 11, the leveling treatment is performed. Concretely, in theprocess of the leveling treatment, the concentration of the solvent inthe gas supplied into the chamber 201 is set to 100% and kept at thisvalue. Moreover, the temperature of the whole temperature control plate206 is set at 23° C., and kept at this value. Thereafter, the dryingtreatment is performed so as to vaporize the solvent in the chamber 201whose pressure has been reduced. At this time, in the related-artmethod, the film thickness of the liquid film is not measured. Moreover,the temperature of the temperature control plate is kept constant.

In the related-art method, when the film thickness of the liquid film 16is measured in the respective points P₁, P₂, P₃ during the levelingtreatment, as shown in FIG. 28B, the film thickness decreases in thepoint P₃ on the substrate 11. Conversely, it is seen that the filmthickness increases in the point P₁.

Moreover, at the end time of the leveling treatment, the film thicknessof the liquid film 16 in the point P₁ was 18 μm, and the film thicknessof the liquid film 16 in the point P₃ was 2 μm. It is seen that the filmthickness difference of the liquid film 16 is large on the middleportion and peripheral edge of the substrate 11. In this manner, in therelated-art method, the concave/convex portion in the surface generatedin the process of formation of the liquid film disappears by theleveling treatment, and the whole film tends to be thick in the middleportion and thin in the peripheral edge.

Furthermore, thereafter, the drying treatment is performed in thereduced pressure state. In the related-art drying treatment, when thesolvent of the liquid film is vaporized, the film thickness is notcontrolled so as to be within the given range as described above.Therefore, when the drying treatment is performed, film thickness sag(=decrease of the film thickness) of the peripheral edge is furtherpromoted in the process of vaporization of the solvent, and the solidfilm is formed.

Another method will next be described. In the same manner as in thepresent embodiment, at the leveling treatment time, this methodcomprises: measuring and monitoring the film thickness of the liquidfilm in the respective points P₁, P₂, P₃; controlling the concentrationof the solvent in the gas supplied into the chamber 201; and using thetemperature control plate to control the temperature distribution of thesubstrate. Thereafter, the film thickness is not measured at the dryingtreatment time. Moreover, while the temperature of the temperaturecontrol plate is kept to be constant at 23° C., the solvent is vaporizedand the drying treatment is performed.

In this method, as shown in FIG. 28C, immediately after the end of theleveling treatment, the film thickness of the liquid film is flattedover the whole surface, but at the drying treatment time the filmthickness of the point P₃ remarkably decreases as compared with thepoint P₁. The finally formed film is flatted in the middle portion, butthe film thickness decreases in the peripheral edge.

FIG. 29A shows the distribution of the film thickness of the solid filmformed in temperature profiles shown in FIGS. 28A to 28C. Moreover, FIG.29B shows the film thickness uniformity of the solid film. In FIGS. 29A,29B, A denotes the solid film formed in the temperature profile shown inFIG. 28A, B denotes the solid film formed in the temperature profileshown in FIGS. 28B, and C denotes the solid film formed in thetemperature profile shown in FIG. 28C.

Note that FIG. 29A is a sectional view of the solid film formed on thesubstrate, and shows the change of the film thickness.

Thereby, it is seen that in B, already at the leveling treatment time,the film thickness of the liquid film largely deviates, and that a largefilm thickness difference is generated in the positions on theperipheral edge (=coordinate: ±100) and middle portion (=coordinate: 0)after the drying treatment. Moreover, in C, at the leveling treatmenttime, the film thickness difference is within the given range in eachpoint, but the film thickness difference is generated at the dryingtreatment time, and the film thickness difference is generated on theperipheral edge and middle portion.

As shown in FIG. 29B, the film thickness uniformity was 20% in B and 10%in C. On the other hand, in A, the solid film whose film thickness issubstantially uniform at 400 nm and which has a flatted state is formedover the whole surface of the substrate. Moreover, the film thicknessuniformity of A is 1.0%, and is largely enhanced as compared with B andC.

Thereby, when the film thickness of the liquid film at each treatmenttime is measured and monitored and controlled to be within the givenrange as needed, as in the present embodiment, a solid film having aflat surface and uniform film thickness can be formed.

As described above, in the present embodiment, during the processes ofthe leveling and drying treatments, the change of the film thickness ofthe liquid film 16 is monitored, and each parameter can be adjusted tohave the appropriate value while each treatment is performed. Therefore,in the present embodiment, it is possible to obtain a high-precision(i.e., flat) film thickness distribution in the solid film (e.g.,photoresist film).

For example, as a result of the monitoring, in the leveling treatment,when the concentration of the solvent in the gas supplied into thechamber is gradually lowered during the treatment step, the solvent canbe prevented from being unnecessarily applied to the surface of theliquid film 16 and the film thickness distribution can be prevented frombeing disordered. Moreover, in the drying treatment, the temperaturedifference between the peripheral edge and middle portion of thesubstrate 11 is controlled, and thereby the solid content movement isprevented from being caused by the difference in physical properties ofthe liquid film between the middle portion and peripheral edge of thesubstrate with the progress of the drying, that is, vaporization of thesolvent.

The present embodiment can be modified without departing from the scopeof the present invention.

The leveling treatment can be changed as follows. In the presentembodiment, the concentration of the solvent in the chamber 201 duringthe leveling treatment is uniformed in the chamber 201 as a treatmentcontainer, but this is not limited. For example, a concentrationdistribution may be disposed in the plane of the liquid film 16. In thiscase, as shown in FIG. 30, a supply port 211 for supplying the gasincluding the solvent into the chamber 201 may be constituted to bemovable in the plane of the liquid film 16. Moreover, the substrate 11itself may be constituted so as to be movable.

In this case, it is possible to adjust the concentration of the solventin the gas supplied onto the liquid film surface in accordance with thefilm thickness of the liquid film 16 and to flat the surface. Moreover,with the method for controlling the film thickness of each point tosatisfy the desired value, it is unnecessary to control all theparameters, such as the concentration of the solvent and temperaturedistribution of the substrate 11, and any one parameter may becontrolled.

Moreover, in the present embodiment, in the leveling and dryingtreatments, the concentration of the solvent and the temperaturedistribution of the temperature control plate are not limited to theabove-described values, and can be changed in accordance with type ofcoating solution used, substrate, and coating method.

Furthermore, the solvent for use in the leveling treatment is notlimited to the solvent of the material used in the liquid film 16, andany material that functions with respect to the liquid film 16 so as topromote the fluidity of the liquid film 16 may be used. Additionally, asolvent including a surface-active agent which functions so as to lowerthe surface tension of the liquid film 16 may also be used.

Moreover, in the present embodiment, the fluidity of the surface ispromoted by adding the solvent to the surface of the liquid film 16 andthe leveling is performed, but this is not limited.

In the leveling treatment, the gas including the solvent with the givenconcentration is supplied into the chamber 201, and the temperaturecontrol plate 206 is used to control the temperature of the substrate11, so that the surface can be flatted.

Here, the leveling treatment will concretely be described with referenceto FIGS. 31A to 31C. FIG. 31A is a diagram showing the change of thefilm thickness of the liquid film in each position on the substrate withtime in the leveling treatment according to the fifth embodiment, FIG.31B is a diagram showing the change of solvent concentration in gassupplied into the chamber with time in the leveling treatment accordingto the fifth embodiment, and FIG. 31C is a diagram showing the change oftemperature of the middle and peripheral edge plates in the levelingtreatment according to the fifth embodiment.

First, the substrate 11 is conveyed into the chamber 201 of theleveling/drying treatment apparatus 200, and laid and fixed onto thestage 205. At this time, the temperature T_(c) of the middle plate 206 adisposed in the stage 205 is set at 30° C., and the temperature T_(r) ofthe peripheral edge plate 206 b is set at 23° C.

Thereafter, the leveling treatment is started so as to flat the surfaceof the liquid film 16. At this time, as shown in FIG. 31B, during theleveling treatment, the concentration of the solvent in the gas suppliedinto the chamber 201 is kept constant.

For example, the concentration of the solvent is kept at 50%.

Immediately after the leveling treatment is started, as shown in FIG.31C, the film thickness of the liquid film 16 largely deviates in therespective points P₁, P₂, P₃ on the substrate 11.

Moreover, as shown in FIG. 31C, after the leveling treatment starts, thetemperature T_(r) of the peripheral edge plate 206 b is lowered to about30° C. As a result, the temperature of the middle portion of thesubstrate varies greatly from that of the peripheral edge of thesubstrate.

In this leveling treatment, the temperature of the middle portion of thesubstrate 11 is raised, the viscosity of the liquid film 16 is reduced,and the fluidity is further promoted. Thereby, the surface can beflatted in the same manner as in the case in which the solvent issupplied to the surface of the liquid film 16.

Furthermore, at this time, the temperature of the peripheral edge of thesubstrate 11 is lowered to about 20° C. During the leveling treatment,the temperature of the peripheral edge of the substrate 11 is set to belower than that of the middle portion. Therefore, it is possible toinhibit the solid content from moving toward the middle portion from theperipheral edge of the substrate 11.

In the present embodiment, in the drying treatment, the inside of thechamber 201 is exhausted, and the solvent of the liquid film isvaporized in this reduced pressure state, but this is not limited, andcan be changed as follows.

For example, in order to promote the vaporization of the solvent, theair current by the inactive gas (e.g., N₂, Ar) is formed on the surfaceof the liquid film 16, and the drying treatment can be performed. Inthis case, as shown in FIG. 32, in the leveling/drying treatmentapparatus 200, the gas control unit 202 is used. The inactive gas suchas N₂ is fed into the chamber 201 from above the substrate 11, the aircurrent is supplied to the surface of the liquid film 16 to vaporize thesolvent, and the drying treatment can be performed. Here, as describedabove, in the leveling/drying treatment apparatus 200, the temperaturecontrol plate 206 is disposed on the stage 205 on which the substrate 11is laid. Moreover, if there is no particular problem, air may be used informing the air current.

Note that the supply of gas from above the substrate 11 is not limited.In the leveling/drying treatment apparatus 200, the gas is fed into thechamber 201 from below the substrate 11, and may be exhausted from abovethe substrate 11. Moreover, the air current may flow in one direction(transverse direction) with respect to the surface of the substrate 11.For example, the gas may be supplied through one end of the substrate 11and exhausted through the other end.

Here, this drying treatment will concretely be described with referenceto FIGS. 33A to 33C. FIG. 33A is a diagram showing the change of thefilm thickness of the liquid film in each position on the substrate withtime in the leveling and drying treatments according to the fifthembodiment, FIG. 33B is a diagram showing a change of a flow rate of N₂gas supplied into the chamber with time in the leveling and dryingtreatments according to the fifth embodiment, and FIG. 33C is a diagramshowing the change of temperature of the middle and peripheral edgeplates in the leveling and drying treatments according to the fifthembodiment. FIGS. 33A to 33C continuously show the states of theabove-described leveling and drying treatments.

As shown in FIG. 33A, the leveling treatment is performed, and thedifference of the film thickness of each point is controlled to bewithin the given range. Thereafter, the drying treatment is performed,and the solvent is vaporized until the liquid film 16 obtains apredetermined film thickness (e.g., 400 nm).

After the leveling treatment ends, the drying treatment is performed. Inthe drying treatment, the inactive gas (e.g., N₂, Ar) is fed into thechamber 201, and the air current is formed on the surface of the liquidfilm 16 to vaporize the solvent in the liquid film. At the dryingtreatment time, N₂ gas is supplied into the chamber 201, and an aircurrent is formed in the surface of the liquid film 16. As shown in FIG.33B, at the drying treatment time, the flow rate of the N₂ gas isincreased to about 5 L/min.

Moreover, at this time, in the process of the drying treatment, thetemperature of the substrate 11 is controlled. Here, as shown in FIG.33C, the temperature T_(c) of the middle plate 206 a is kept at about23° C. as in the leveling treatment time. The temperature T_(r) of theperipheral edge plate 206 b is gradually lowered to about 13° C. from15° C. of the leveling treatment time. Thereafter, in the process of thedrying treatment, the temperature T_(r) of the peripheral edge plate 206b is kept at about 13° C.

In this manner, during the leveling treatment, the temperature of theperipheral edge of the substrate 11 is set to be lower than that of themiddle portion, and it is possible to reduce the movement of the solidcontent toward the middle portion from the peripheral edge.

In the present embodiment, when the solvent of the liquid film 16 issufficiently vaporized, and the film thickness of the liquid film 16reaches the predetermined film thickness in the respective points P₁,P₂, P₃ on the substrate 11 and does not change, the drying treatment isended.

In the present embodiment, in this case, during the drying treatment,the flow rate of the air current is changed as needed, and the filmthickness of the liquid film 16 can be inhibited from being lowered onthe peripheral edge of the substrate 11. For example, the temperature ofthe peripheral edge of the substrate 11 is lowered, and the temperaturedifference from the middle portion is generated. Additionally, the aircurrent may also be increased toward the end from the initial stage ofthe drying in accordance with the film thickness in the respectivepoints P₁, P₂, P₃ on the substrate 11. In this method, the solid contentof the liquid film moved toward the middle portion from the peripheraledge of the substrate is pushed back toward the peripheral edge and thedrying may be performed.

Here, this drying treatment will be described with reference to FIGS.34A to 34C. FIG. 34A is a diagram showing the change of the filmthickness of the liquid film in each position on the substrate with timein the leveling and drying treatments according to the fifth embodiment,FIG. 34B is a diagram showing the change of the flow rate of N₂ gassupplied into the chamber with time in the leveling and dryingtreatments according to the fifth embodiment, and FIG. 34C is a diagramshowing the change of temperature of the middle and peripheral edgeplates in the leveling and drying treatments according to the fifthembodiment. FIGS. 34A to 34C show the states of the above-describedleveling and drying treatments.

As shown in FIG. 34A, the leveling treatment is performed, and thedifference of the film thickness is controlled to be within the givenrange. After the leveling treatment, the drying treatment is performeduntil the liquid film 16 obtains the predetermined film thickness (e.g.,400 nm).

In the drying treatment, an inactive gas (e.g., N₂, Ar) is fed into thechamber 201, and an air current is supplied onto the surface of theliquid film 16 to vaporize the solvent. Concretely, N₂ gas is fed intothe chamber 201, and the air current is formed over the surface of theliquid film 16. At this time, as shown in FIG. 34B, the flow rate of thegas is increased to 5 L/min from the start time of the drying treatment.Thereafter, the flow rate is substantially kept, and increased to about2500 L/min in an index function manner at the point of end.

In the drying treatment, the temperature of the substrate 11 iscontrolled. Here, as shown in FIG. 34C, the temperature T_(r) of theperipheral edge plate 206 b is gradually lowered to about 17° C. fromthe temperature (=20° C.) of the leveling treatment time. Thereafter, inthe process of the drying treatment, the temperature T_(r) is maintainedconstant. On the other hand, the temperature T_(c) of the middle plateis lowered to about 23° C. (=room temperature) from the temperature(=30° C.) of the leveling treatment time. Thereafter, the temperatureT_(c) is maintained constant.

In the present embodiment, when the solvent of the liquid film 16 issufficiently vaporized, and the film thickness of the liquid film 16reaches a predetermined film thickness (e.g., 400 nm) in the respectivepoints P₁, P₂, P₃ on the substrate 11, and does not change, the dryingtreatment is ended.

Moreover, when an air current is supplied to the liquid film 16 toperform the drying treatment, a part of the leveling/drying treatmentapparatus 200 is changed, and an air current control plate 212 may bedisposed in the position of the outer periphery of the substrate 11 asshown in FIG. 35. Since the air current control wall 212 is disposed inthis position, the air current is reduced on the peripheral edge of thesubstrate 11, and rapid drying (i.e., vaporization of the solvent) canbe inhibited. Therefore, controllability of the film thickness of theliquid film 16 is enhanced in the peripheral edge of the substrate 11.

In the present embodiment, when the rotation of the substrate iscombined at the drying treatment time, the film thickness difference ofthe liquid film is controlled to be within the given range, and thesolvent can be vaporized.

In this case, a part of the leveling/drying treatment apparatus 200 ischanged, and a rotation system stage 213 is disposed as shown in FIG.36. While the substrate 11 is laid and fixed onto the rotation systemstage 213, the leveling and drying treatments are performed. Moreover,the rotation system stage 213 is connected to the analysis unit 210. Theanalysis unit 210 sends an indication of a rotation speed to therotation system stage 213 based on the measurement result of the opticalsystem for film thickness measurement 207, and the rotation speed of thesubstrate 11 is controlled.

For example, after the leveling treatment, the gas in the chamber 201 isexhausted, and the drying treatment is performed in the reduced pressurestate. During the drying treatment, the substrate 11 starts to berotated at a predetermined timing. While the rotation speed of thesubstrate 11 is increased, the film thickness of the liquid film 16 iscontrolled in each point.

This drying treatment will be described with reference to FIGS. 37A to37C. FIGS. 37A to 37C continuously show the states of theabove-described leveling and drying treatments.

As shown in FIG. 37A, after the leveling treatment, the difference ofthe film thickness in each point is controlled to be within the givenrange, the solvent of liquid film 16 is vaporized until a predeterminedfilm thickness (e.g., 400 nm) is obtained, and the drying treatment isperformed.

At this time, the drying treatment is performed in a reduced pressurestate in the chamber 201. In order to vaporize the solvent in the liquidfilm 16, a vacuum pump disposed in the exhaust unit 203 is used toexhaust the atmosphere in the chamber 201 to the outside at −60Torr/sec. Concretely, as shown in FIG. 37B, the pressure in the chamber201 is kept at about 760 Torr during the leveling treatment. Thereafter,the atmosphere in the chamber 201 is exhausted at −60 Torr/sec, andpressure in the chamber 201 is set to about 2 Torr corresponding to thevapor pressure of the solvent. Moreover, during the drying treatment,the pressure the chamber 201 is kept at 2 Torr.

Moreover, as shown in FIG. 37C, the leveling treatment is performedwhile the substrate 11 is in a stationary state (=rotation speed of 0rpm). The substrate 11 is rotated from the middle of the dryingtreatment. Towards the end of the drying treatment, the rotation speedis rapidly increased in the index function manner until the rotationspeed is about 300 rpm.

In this case, the rotation speed of the substrate is increased inaccordance with the film thickness of the liquid film 16, the flow ofthe liquid film 16 to the middle portion from the peripheral edge isinhibited by the centrifugal force, and the solid content can beinhibited from moving onto the middle portion. Moreover, this method canalso be applied to the drying treatment in which an air current issupplied, as described above.

This drying treatment will be described with reference to FIGS. 38A to38C. FIGS. 38A to 38C show the states of the above-described levelingand drying treatments. FIG. 38A is a diagram showing the change of thefilm thickness of the liquid film in each position on the substrate withtime in the leveling and drying treatments according to the fifthembodiment, FIG. 38B is a diagram showing the change of the flow rate ofN₂ gas supplied into the chamber with time in the leveling and dryingtreatments according to the fifth embodiment, and FIG. 38C is a diagramshowing the change of the rotation speed of the substrate in theleveling and drying treatments according to the fifth embodiment.

As shown in FIG. 38A, after the leveling treatment, the difference infilm thickness at each point is controlled to be within a given range,the solvent of liquid film 16 is vaporized until a predetermined filmthickness (e.g., 400 nm) is obtained, and the drying treatment isperformed.

At this time, after the end of the leveling treatment, an inactive gas(e.g., N₂, Ar) is fed into the chamber 201, and the air current isformed on the surface of the liquid film 16 to vaporize the solvent inthe liquid film 16. Concretely, as shown in FIG. 38B, N₂ gas is fed intothe chamber 201 at a flow rate of about 5 L/min, and an air current isformed over the surface of the liquid film 16.

Moreover, as shown in FIG. 38C, the leveling treatment is performedwhile the substrate 11 is in the stationary state (=rotation speed of 0rpm). Thereafter, the substrate 11 starts to be rotated during thedrying treatment. The rotation speed of the substrate is rapidlyincreased in the index function manner until the rotation speed reachesabout 300 rpm. In this case, the rotation speed is increased inaccordance with the film thickness of the liquid film 16. By thecentrifugal force, the liquid film 16 is pushed back onto the peripheraledge, and the solid content can be inhibited from moving onto the middleportion.

Note that as a result of the monitoring/controlling of the filmthickness of each point, in one example, the flow rate of the aircurrent and the rotation speed are increased in the index functionmanner, but this is not limited. A timing for controlling the rotationspeed of the substrate and starting the rotation can be changed inaccordance with the state of the film thickness. For example, when theliquid film obtains a predetermined film thickness, the rotation speedof the substrate may linearly (=linear function manner) be increased tocontrol the film thickness.

This drying treatment will be described with reference to FIGS. 39A to39C. FIG. 39A is a diagram showing the change of the film thickness ofthe liquid film in each position on the substrate with time in theleveling and drying treatments according to the fifth embodiment, FIG.39B is a diagram showing the change of the flow rate of N₂ gas suppliedinto the chamber with time in the leveling and drying treatmentsaccording to the fifth embodiment, and FIG. 39C is a diagram showing thechange of rotation speed of the substrate in the leveling and dryingtreatments according to the fifth embodiment. FIGS. 39A to 39Ccontinuously show the states of the above-described leveling and dryingtreatments.

As shown in FIG. 39A, after the leveling treatment, the difference inthe film thickness is controlled to be within a given range in therespective points P₁, P₂, P₃ on the substrate 11, the solvent of theliquid film 16 is vaporized until a predetermined film thickness (e.g.,400 nm) is obtained, and a drying treatment is performed.

At this time, after the leveling treatment ends, an inactive gas (e.g.,N₂, Ar) is fed into the chamber 201, and an air current is supplied ontothe surface of the liquid film 16 to vaporize the solvent. Concretely,as shown in FIG. 39B, N₂ is supplied into the chamber 201 at about 5L/min, and an air current is formed over the surface of the liquid film16.

Moreover, as shown in FIG. 39C, the leveling treatment is performedwhile the substrate 11 is in the stationary state (=rotation speed of 0rpm). At the drying treatment time, when the film thickness of theliquid film 16 reaches the predetermined value, the substrate 11 startsto be rotated. In the present embodiment, when the film thickness of theliquid film 16 reaches 6.0 μm, the substrate 11 starts to be rotated.The rotation speed of the substrate 11 is linearly (=linear functionmanner) increased to reach about 300 rpm. The rotation speed of thesubstrate 11 is increased in accordance with the film thickness of theliquid film 16. By the centrifugal force, the liquid film 16 isinhibited from flowing into the middle portion from the peripheral edge,and the solid content can be inhibited from moving onto the middleportion.

In the present embodiment, in one example, the drying treatment isperformed until the film thickness of the solid film is substantiallyobtained (e.g., 400 nm), and the film thickness of the liquid film 16does not change. Concretely, the treatment is performed until theconcentration of the solid content in the liquid film 16 reaches 80% ormore. After the drying treatment, a baking treatment is performed tovaporize the remaining solvent, and the film is stabilized. However, theprocess is not limited to the above-described process. For example,after ending the drying treatment in a stage in which the film thicknessof the liquid film still changes, a baking treatment can also beperformed. In this case, the drying treatment ends, when the liquid film16 reaches predetermined film thickness (e.g., 1.0 μm). Thereafter, thebaking treatment is performed to stabilize the film, and a solid filmhaving a film thickness of 400 nm is formed.

Note that, here, to prepare for the supply of the air current to theliquid film 16, the air current control wall described above withreference to FIG. 35 can be disposed in the leveling/drying treatmentapparatus 200 shown in FIG. 36.

As described above, in the present embodiment, as needed, the filmthickness in each point is monitored, the leveling and drying treatmentsare performed, and the respective treatment parameters (=concentrationand pressure of the solvent in the chamber, temperature distribution ofthe substrate, air current required for the drying treatment, androtation speed of the substrate) are controlled until these treatmentsend, but the present invention is not limited to this.

For example, as described hereinafter, in the leveling treatment and inthe initial stage of the drying treatment, a control function is derivedby fitting the value of each treatment parameter with respect to time.Thereafter, the control may also be executed based on the derivedcontrol function until the end of each treatment.f(P,t)=0f(T,t)=0f(V,t)=0f(R,t)=0

P: pressure in the chamber.

T: temperature of the substrate

V: flow rate of the air current

R: rotation speed of the substrate

t: time

Moreover, as described above, after once deriving the control function,the control function is stored in the analysis unit 210. In thetreatment of the second and subsequent substrates, without monitoringthe film thickness of the liquid film 16, each treatment can beperformed while referring to the control function of the analysis unit210.

For example, to perform the drying treatment by the control of therotation speed of the substrate 11, from start time t_(A) of the dryingtreatment till time t_(B), the film thickness of the liquid film 16 ineach point is measured and monitored, and the rotation speed of thesubstrate 11 is controlled till the initial stage. FIG. 40A showstendency of the change of the film thickness of the liquid film 16 atd=−0.16t+10 (d: film thickness, t: time). Moreover, FIG. 40B shows therotation speed of the substrate in accordance with the film thicknesschange shown in FIG. 40A. At this time, when the change of the rotationspeed of the substrate with respect to the change with time t_(A) tot_(B) is derived as the function by the fitting, the rotation speed ofthe substrate: R=2.5e^(0.7t). Therefore, from time t_(B) until end timet_(C) of the drying treatment, the rotation speed of the substrate 11 iscontrolled in accordance with the function: R=2.5e^(0.7t).

For the second and subsequent substrates, the rotation speed of thesubstrate 11 may be controlled in accordance with the control function:R=2.5e^(0.7t).

Note that the solid content does not move with the movement of thesolution in the transverse direction of the substrate. In this case, therespective conditions such as the temperature of the substrate at thedrying time, air current of the drying treatment, atmosphereconcentration in the chamber, and pressure are changed using a testsubstrate beforehand. Moreover, the film thickness is measured byreflected light measurement in a plurality of points including at leastthe substrate center, coating start position, and coating end position.From these results, a condition on which the interference fringes of thereflected light are generated with respect to the film thickness of theliquid film in one direction, or toward the outer periphery from thesubstrate center may be determined.

As described above, the present embodiment comprises: forming a liquidfilm; subsequently continuously performing a leveling and dryingtreatments; controlling the film thickness difference of the liquid filmas needed in each treatment step; and forming the film including thesolid content on the substrate. Therefore, when the film thickness ofthe liquid film in each point is within the predetermined range afterforming the liquid film on the substrate, the drying treatment can alsobe performed without performing the leveling treatment. Moreover, afterthe leveling treatment, depending on the material of the liquid film,the solid content hardly moves during the drying treatment. In thiscase, as described above, the film thickness is not particularlycontrolled, the solvent of the liquid film is vaporized in therelated-art method, and the drying treatment can also be performed. Inthis case, a magnitude relation of the temperature may be reversed inthe middle portion and peripheral edge of the substrate so as to performthe drying treatment. That is, in the process in which the dryingtreatment is performed, the temperature of the middle portion of thesubstrate is set to be lower than that of the peripheral edge, so thatthe solvent of the liquid film can also be vaporized.

Additionally, the constitution of the leveling/drying treatmentapparatus can appropriately be changed without departing from the scopeof the present invention, and the substrate to be actually coated andsolution may be used to carry out the experiment described in thepresent embodiment and to determine each condition.

SIXTH EMBODIMENT

FIGS. 41A to 41E are process sectional views showing a manufacturingprocess of a semiconductor apparatus according to a sixth embodiment ofthe present invention.

First, as shown in FIG. 41A, a liquid film 302 including a resistsolution is formed on a substrate 301. The resist solution is obtainedby dissolving a chemical amplification type resist material (firstmaterial) obtained by blending a resin, dissolution inhibitor material,and acid generating material at a given ratio in ethyl lactate(solvent). The resist solution is adjusted so as to set the filmthickness of the resist film (solid film) including the resist materialfinally to 300 nm in the state in which the solvent in the liquid filmis completely evaporated. Note that the substrate 301 includes thesemiconductor substrate, and is in the middle of the manufacturingprocess of the semiconductor apparatus.

An outline of the liquid film forming apparatus for use in forming theliquid film 302 is shown in FIG. 42.

The apparatus shown in FIG. 42 will next be described. As shown in FIG.42, a substrate hold portion 330 on which the substrate 301 is mountedis connected to a driving system 331 which rotates centering on thesubstrate 301. Moreover, a solution discharge nozzle 332 whichdischarges the solution and which can be moved in the diameter directionby a nozzle driving system 333 is disposed above the substrate 301. Thesolution discharge nozzle 332 is connected to a solution supply pump 335which supplies the solution to the solution discharge nozzle 332 via asolution supply tube 334. The discharge speed from the solutiondischarge nozzle 332 is controlled by controlling a solution supplypressure from the solution supply pump 335.

The solution discharge nozzle 332 starts movement substantially from thecenter of the substrate 301 by the nozzle driving system 333, andcontinuously supplies the solution onto the substrate 301 whilesubstantially moving to the edge of the substrate 301. The solutionsupply ends when the solution discharge nozzle reaches the edge of thesubstrate 301. In movement start and end points of the solutiondischarge nozzle, solution cut-off functions 336 a, 336 b are disposed.The solution cut-off function 336 a in the movement start point cuts offthe solution discharged from the solution discharge nozzle 332 until therotation speed of the substrate hold portion 330, movement speed of thenozzle driving system 333, and discharge speed from the solutiondischarge nozzle 332 reach predetermined values required at the coatingstart time, and prevents the solution from reaching the substrate 301.Moreover, the solution cut-off function 336 b in the movement end pointis on standby above the edge of the substrate 301 so as to prevent thesolution from being supplied to the edge of the substrate 301, and cutsoff the solution discharged from the nozzle 332, when the solutiondischarge nozzle 332 reaches the edge of the substrate 301. The solutionis thus prevented from reaching the substrate 301.

While the solution is supplied onto the substrate 301, the rotationspeed of the substrate hold portion 330, movement speed of the nozzledriving system 333, and discharge speed from the solution dischargenozzle 332 are managed by a rotation driving control unit 338, nozzledriving control unit 337, and solution supply pump 335. Note that acontroller 339 for controlling the pump 335 and control units 337, 338is disposed upstream.

The controller 339 determines the rotation speed of the substrate 301,movement speed of the solution discharge nozzle 332, and discharge speedfrom the solution discharge nozzle 332 based on position information ofthe solution discharge nozzle 332 on the substrate 301, and instructsthe rotation driving control unit 338, nozzle driving control unit 337,and solution supply pump 335. When these operated based on theinstruction, the solution is supplied in a spiral form onto thesubstrate 301. The solution supplied onto the substrate 301 spreads, andis combined with the adjacent liquid film to form one liquid film 302 onthe substrate 301.

For the resist solution for use in the above-described two apparatuses,a solution having a small solid content, and low viscosity in a range ofabout 0.001 Pa·s to 0.010 Pa·s (1 cp to 10 cp) is used.

The discharging of the solution onto the substrate 301 from the solutiondischarge nozzles 322, 332 by the above-described apparatus will bedescribed with reference to FIG. 43. FIG. 43 is a sectional view for usein the description of the discharge state of the solution by the liquidfilm forming apparatus shown in FIG. 42. As shown in FIG. 43, thesolution discharge nozzles 322, 332 spirally discharge solutions 342 a,342 b, 342 c in adjacent positions The spirally discharged solutions 342a, 342 b, 342 c spread by the fluidity of the solutions with time toform one liquid film. Moreover, as shown in FIG. 41A, the surface of theconnected liquid film has a substantially flat shape by the surfacetension of the liquid.

Subsequently, the solvent in the liquid film 302 is removed. To removethe solution, the substrate having the liquid film formed on the mainsurface thereof is exposed under a reduced pressure, or heated using anoven or hot plate, the solvent in the liquid film is evaporated, and thesolvent can be removed.

When the removal of the solvent proceeds to some degree, as shown inFIG. 41B, a first resist layer 311 of the lower layer including theresist material is formed from a direction of a lower part of the liquidfilm 302. Moreover, in the surface layer of a liquid film 302 a in whichthe solvent is being evaporated, the viscosity is in a high state.

To remove the solvent, the film thickness of the first resist layer 311being formed is measured. The film thickness of the first resist layer311 can be obtained, for example, by irradiating the liquid film 302with a light from the light source having a single wavelength as acollimated light, monitoring a reflected light intensity, capturing aninterference waveform in the liquid film, and analyzing the waveformusing an optical constant (refractive index and attenuation coefficient)of the liquid film.

When the film thickness of the first resist layer 311 being formedreaches 290 nm, the removing of the solvent once stops.

Subsequently, as shown in FIG. 41C, the removal of the solvent is oncestopped, a second solution (second material solution) 303 in which thedissolution inhibitor material included in the above-described resistmaterial is dissolved in ethyl lactate is sprayed onto the surface ofthe liquid film 302 in the process of solidifying, and the dissolutioninhibitor material is supplied to the surface of the liquid film 302 a.To spray the second solution 303, for example, the substrate 301including the liquid film 302 a remaining on the surface thereof is laidin a container filled with a mist solution.

Moreover, to spray the second solution 303, the substrate 301 isrotated, and the solution can be supplied in a mist form substantiallyfrom above the rotation center of the substrate 301. When the substrate301 is rotated, the air current directed toward the outside of thesubstrate substantially from the rotation center is generated. When themist solution is supplied substantially from above the rotation center,the mist solution rides on the air current, and the solution issubstantially uniformly sprayed over the whole surface of the substrate301.

Thereafter, the solvent (ethyl lactate) is continuously removed, thesolvent in the liquid film is completely removed, and a solid resistfilm (solid film) 310 is formed as shown in FIG. 41D. The resist film310 is constituted of the first resist layer 311 and second resist layer312 on the first resist layer 311. The second resist layer 312 has afilm thickness of 10 nm. As a result of material analysis such as XPS,it has been confirmed that much dissolution inhibitor is distributed inthe second resist layer 312 as compared with the first resist layer 311.

According to the above-described method, the dissolution inhibitormaterial is added to the surface of the liquid film 302 a during thedrying, the solvent is further removed, and it is possible to easilyform the resist film 310 which has a different composition only in thesurface layer. Since it is unnecessary to separately form the resistfilm having the different composition, a manufacturing time of theresist film different in the composition in the film thickness directionis shortened.

Subsequently, as shown in FIG. 41E, after exposure and post-exposurebake treatment (PEB) are performed, development is performed to form aresist pattern 313.

As shown in FIG. 41E, the upper part of the first resist layer 311 isrounded, but the upper surface of the second resist layer 312 ismaintained in a rectangular shape.

The exposure, post-exposure bake treatment, and development of thechemical amplification type resist film will briefly be described. Whenthe acid generating material in the chemical amplification type resistfilm is irradiated with light, the acid generating material isdecomposed and acid molecules are generated. Moreover, the resist filmis heated, then the acid molecules decompose the dissolution inhibitormaterial, and the dissolution inhibitor material is changed into amolecular structure which can be dissolved in a developer.

The shape of the resist pattern prepared from the resist film formed inthe related-art method is shown in FIG. 44. A resist pattern 351 shownin FIG. 44 is prepared on the same conditions as those of the exposureand development of the resist pattern 313 shown in FIG. 41E.

The reason why the shape of the upper surface of the second resist layer312 is maintained in the rectangular shape will be describedhereinafter. The upper surface of the resist film is exposed to thedeveloper for a long time. Therefore, with the resist film in which thedissolution inhibitor material is uniformly distributed, the upper partis rounded. However, when much dissolution inhibitor is included in thesurface as in the present embodiment, the development speed in the upperpart can be lowered, and the surface shape can be rectangular.

As described above, when the present method is used, the profile of theresist pattern can easily be improved.

Note that in the method described in the present embodiment, theevaporation is not performed at all, the second solution is suppliedonto the liquid film in this state, and the dissolution inhibitormaterial in the second solution is diffused in the liquid film.Therefore, in the state in which the solvent is removed to some degreeand the resist film is formed in the lower part, the second solution hasto be supplied onto the liquid film.

Note that in the present embodiment the second resist layer 312including much dissolution inhibitor is formed in a range of 10 nm fromthe surface, but this is not limited. This differs by the exposure,post-exposure bake, and development conditions. Therefore, in order toobtain the desired resist pattern, experiments are repeatedly conducted,and the film thickness width including much dissolution inhibitor andthe amount of the dissolution inhibitor may be optimized. Moreover, theresist film described in the present embodiment is defined as aphoto-sensitive resin film which contains photosensitive polyimide.

The film thickness of the layer including much dissolution inhibitor isdetermined by the timing to supply the second solution. That is, thethickness is determined by the amount of the liquid film formed on thesolid film being formed. Therefore, in the method described in thepresent embodiment, it is important to grasp the evaporation state ofthe solvent.

For the resist solution for use in the above-described two apparatuses,the solution containing a large amount of solvent in the liquid film isused. Therefore, much time is required for removing the solvent, and itis easy to grasp the evaporation state of the solvent. Therefore, in themethod described in the present embodiment, the above-described liquidfilm forming apparatus is preferably used.

Note that the method described in the present embodiment can also beapplied to the liquid film formed by a spin coating method. Moreover,the present invention can also be applied to the liquid film prepared invarious methods such as a method of discharging or spraying the solutionto form the film, and a method of using the meniscus phenomenon to formthe film, as disclosed in Jpn. Pat. Appln. KOKAI Publication Nos.2-220428, 6-151295, 7-321001, 2001-310155, and 11-243043.

Moreover, in the present embodiment, the same dissolution inhibitormaterial as that contained in the resist material is used as thedissolution inhibitor material, but this is not limited. As long as thedesired resist pattern profile is obtained, any available material mayalso be used. Also in this case, the experiments are repeatedlyconducted, the material is selected, and the film thickness width to beadded and addition amount may be optimized.

Moreover, in the present embodiment, the removal of the solvent is oncestopped, the solution in which the dissolution inhibitor materialincluded in the above-described resist is dissolved in ethyl lactate issprayed onto the liquid film surface in the process of solidification,and thereafter the solvent (ethyl lactate) is continuously removed, butthis is not limited.

For example, while the solvent is removed, the spray amount of thesolution containing the dissolution inhibitor material dissolved in theethyl lactate is increased with time to form the resist film, and it isalso possible to raise the concentration of the dissolution inhibitormaterial in the vicinity of the film surface.

When the resist film is subjected to this treatment, as shown in FIG.45, a rectangular satisfactory resist pattern 361 can be obtained. InFIG. 45, a second resist layer 312′ has a dissolution inhibitor materialconcentration higher than that of the first resist layer 311, and is aresist film which has a profile having the high dissolution inhibitormaterial concentration in the vicinity of the surface. FIG. 45 is asectional view showing the shape of the resist pattern prepared usingthe resist film having the profile which has the higher dissolutioninhibitor material concentration closer to the surface.

Moreover, in the present embodiment, the layer including moredissolution inhibitor in the resist film surface is formed inconsideration of pattern deterioration during the development, but thisis not limited.

For the film in which evaporation of acid at a bake or exposure time asa problem in the chemical amplification type resist is remarkably seen,in consideration of the amount of acid lost at the bake and exposuretime, the acid generating material is selected as the second material,and the resist film containing more acid generating materials may beformed in the resist film surface in a method similar to that of thepresent embodiment. Also with respect to the acid generating materialfor use herein, the experiments are repeatedly conducted for the filmthickness width to be added and addition amount with respect to theavailable material, the material is selected, and the film thicknesswidth to be added and addition amount may be optimized.

The evaporation of acid occurs particularly remarkably in the filmsurface. Therefore, the spray amount of the solution obtained bydissolving the acid generating material in the solvent is preferablyincreased with time.

Of course, to establish both a countermeasure against the evaporation ofacid at the bake or exposure time and a countermeasure against thepattern deterioration at the development time, the dissolution inhibitormaterial and acid generating material are selected as the secondmaterials. The resist film which contains more dissolution inhibitor andacid generating materials in the resist film surface may also be formedin a method similar to that of the present embodiment. Also with respectto the acid generating material for use herein, the experiments arerepeatedly conducted for the film thickness width to be added andaddition amount with respect to the available material, the material isselected, and the film thickness width to be added and addition amountmay be optimized. Also in this case, the spray amount of the solutionobtained by dissolving the acid generating material and dissolutioninhibitor material in the solvent is preferably increased with time.

Examples of the resist as the object to which the present technique isapplied include: chemical amplification type resists which have photosensitivity with respect to deep-UV and vacuum ultraviolet light, suchas KrF, ArF, and F₂ lasers (energy line); chemical amplification typeresists which have photo sensitivity to high and low-accelerationelectron beams (energy lines); and chemical amplification type resistswhich have photo sensitivity to ion beams (energy lines).

Note that the second material is scattered without being dissolved inthe solvent, the solvent remains in the surface layer in the liquidfilm, and the second material may be supplied to the liquid film in thisstate.

Moreover, when a goal of changing the composition of a film thicknessdirection can be achieved using the same composition for the first andsecond materials, the same composition may be used in the first andsecond materials.

SEVENTH EMBODIMENT

It is proposed to use an SiOC composition film whose permittivity islower than that of an SiO₂ film as the interlayer insulating film foruse in the semiconductor apparatus. Since the SiOC composition film isnot dense, the material of a wiring formed in the surface is easilydiffused. Therefore, the dense film such as the SiO₂ film is formed onthe surface of the SiOC composition film in order to prevent thematerial from being diffused.

The SiOC composition film and SiO₂ film have to be thus separatelyformed, and the number of steps has increased. In the presentembodiment, a manufacturing method of the semiconductor apparatus willbe described in which the SiOC composition film and SiO₂ film arecontinuously formed so as to reduce the number of steps.

FIGS. 46A to 46C are process sectional views showing the manufacturingprocess of the semiconductor apparatus according to a seventhembodiment.

First, as shown in FIG. 46A, on a substrate 401, a liquid film 402 isformed including a solution (solid content of 10%) in which the firstmaterial mixed at a ratio of SiO₂:SiOCH₃=1:r₁ is dissolved in thesolvent. The liquid film 402 is formed in a method similar to theforming method described in the first embodiment. Note that thesubstrate 401 includes the semiconductor substrate and is in the middleof the manufacturing process of the semiconductor apparatus.

Subsequently, the substrate 401 on which the liquid film 402 is formedis contained in the pressure reduction chamber. The liquid film isexposed to the reduced pressure substantially equal to the vaporpressure of the solvent included in the liquid film 402, and the solventin the liquid film is slowly removed. The liquid film surface isvertically irradiated with a monochromatic light of 470 nm, thereflected light intensity change is monitored, and the removal processof the solvent is detected.

At a forming time of the liquid film 402, the thickness was about 10 μm(solid content of 10%). As shown in FIG. 46B, in a stage in which theheight of the surface of a liquid film 402 a from the surface of thesubstrate 401 is 1.5 μm, a second solution (second material solution)403 in which a second material mixed at a ratio of SiO₂:SiOCH₃=1:r₂(r₁>r₂) is dissolved in the solvent starts to be introduced into thepressure reduction chamber. A numeral number 411 denotes an SiOCcomposition film.

The second solution 403 is supplied in a state in which the pressure inthe pressure reduction chamber is maintained. It has been confirmed thatthe second solution 403 is sprayed as mist onto the liquid film 402 asurface in the pressure reduction chamber. The ratio r₂ is graduallyreduced toward 0 with respect to a supply start time of the secondsolution 403, the supply amount of SiOCH₃ is changed. Moreover, in astage in which the ratio r₂ turns to 0, the pressure in the pressurereduction chamber is lowered, and the second solution 403 containingonly SiO₂ is introduced into the pressure reduction chamber. After anelapse of 30 seconds, the introduction of the second solution 403 isstopped.

The reduced pressure state is held for one minute after the introductionis stopped. The solvent is removed, and as shown in FIG. 46C, an SiOCcomposition film (solid film) 410 is formed. After the SiOC compositionfilm 410 is formed, the pressure reduction chamber is opened, and thesubstrate 401 is removed. The thickness of the finally formed SiOCcomposition film 410 was 1.2 μm.

A distribution of the film thickness direction of oxygen and carbon withrespect to Si in the obtained SiOC composition film 410 was obtained byanalysis, and the result is shown in FIG. 47. As shown in FIG. 47, it isseen that a layer having a uniform composition of O/Si=1.8, C/Si=0.2 isobtained in the lower-layer film 411 in 0.8 μm from a bottom surface. Ithas been confirmed that a ratio of 0 gradually increases and ratio of Cgradually decreases in an intermediate-layer film 412 between 0.8 μm and1.1 μm. Furthermore, for an upper-layer film 413 having a film thicknessof 0.1 μm on the intermediate-layer film 412, the existence of C is notseen, and it has been confirmed that the film having an SiO₂ compositionis formed.

As described above, in a pressure reduction solvent removal process, thesolution in which SiO₂ is dissolved is supplied to the liquid film beingsolidified, and thereby the low-permittivity interlayer insulatinglayers (0 to 1.1 μm) 411, 412 and upper-layer film (1.1 to 1.2 μm) 413can easily be obtained.

Here, since the film to be finally formed is the SiO₂ film, the solutionwith only SiO₂ dissolved therein may be supplied to the liquid film.However, as described above, the supply amount of SiOCH₃ is graduallyreduced, and finally only SiO₂ is supplied to the liquid film. Thereason why the supply amount of SiOCH₃ is gradually reduced will bedescribed hereinafter. SiO₂ is hydrophilic, and SiOCH₃ has propertiesbetween hydrophilic and hydrophobic properties. For the liquid film,SiO₂ and SiOCH₃ are dissolved in the solvent. When the solution withonly SiO₂ dissolved therein is supplied in the mist form onto the liquidfilm in this state, the properties of the liquid film and solutiondiffer from each other, and the solution with SiO₂ dissolved therein iscondensed. Then, in order to inhibit the solution containing SiO₂ frombeing condensed, the supply amount of SiOCH₃ is gradually reduced, andthe property of the solution is gradually changed.

Note that even with the supply of the second solution onto the liquidfilm, the material included in the second solution is not condensed, andin this case it is unnecessary to gradually change the mixture ratio.

Note that the film having a different composition ratio in the filmthickness direction can be formed even using materials other than theabove-described materials. The material whose composition ratio is knowncan be applied to the formation of the film constituted of any material.

Note that the supply timing of the second solution may be adjusted so asto obtain the desired permittivity. To determine the actual supplytiming and the materials included in the liquid film and secondsolution, the composition ratio of the materials included in the liquidfilm, concentration of the solid content in the liquid film, pressurereduction condition, composition ratio of the materials included in thesecond solution, solid content concentration in the second solution,supply speed into the chamber, and supply time are used as parameters toform a plurality of films. Subsequently, with respect to the formedfilms, the composition of the film thickness direction is analyzed byelement analysis, the permittivity is measured, and the parameters maybe determined so as to obtain the predetermined film conditions.

Moreover, the above-described method is not limited to the formation ofthe SiOC composition film, and can also be applied to the forming of anelectrode or wiring. In this case, an electrode or wiring material maybe used in the first material, and a diffusion inhibitor material may beused in the second material for the purpose of preventing the firstmaterial from being diffused. To determine the materials or supplytiming of the second material, in the same manner as in theabove-described interlayer film formation, the composition ratio of thefirst materials, concentration of the materials dissolved in thesolvent, solvent, pressure reduction condition, composition ratio of thesecond materials, concentration of the materials dissolved in thesolvent, solvent, supply speed into the chamber, and supply time areused as the parameters to form the films. Subsequently, with respect tothe formed films, the composition of the film thickness direction isanalyzed by element analysis, the permittivity is measured, resistancevalue is also measured, and the respective parameters may be determinedso as to obtain the desired film conditions.

EIGHTH EMBODIMENT

The present invention relates to a method of using a coating type silicaglass film to form a film which has a distribution of photo acidgenerating materials on the surface.

As described as the problem in Jpn. Pat. No. 2842909, when theconventional silica glass film is used, acid generated by the chemicalamplification type resist at the exposure time is diffused in the silicaglass film, and problems such as an opening defect are caused.

In Jpn. Pat. No. 2842909, it is described that an acid material isintroduced into the surface of the silica glass film, and therebyopening defects can be prevented.

In an eighth embodiment, a method of using the above-described method tomanufacture the silica glass film (silica dioxide compound) whichcontains the acid material in the surface will be described.

FIGS. 48A to 48E are sectional views showing the manufacturing processesof the semiconductor apparatus according to the eighth embodiment of thepresent invention.

First, as shown in FIG. 48A, on a substrate 501, a liquid film 502 isformed including a first solution in which the first material mixed at aratio of SiO₂:SiOCH₃=:a₁ is dissolved in the solvent. For the formingmethod of the liquid film, a method similar to that described in thefirst embodiment is preferably used. The solid content in the liquidfilm 502 is 3%, and the thickness at the liquid film forming time isabout 10 μm. Note that the substrate 501 includes the semiconductorsubstrate and is in the middle of the manufacturing process of thesemiconductor apparatus.

Subsequently, the substrate 501 on which the liquid film 502 is formedis inserted into the pressure reduction chamber. The liquid film isexposed to the reduced pressure substantially equal to the vaporpressure of the solvent included in the liquid film 502, and the solventin the liquid film 502 is slowly removed. The surface of the liquid film502 is vertically irradiated with monochromatic light of 470 nm, and theremoving process of the solvent is monitored from the reflected lightintensity change.

As shown in FIG. 48B, in a stage in which the height of the surface of aliquid film 502 a is 0.4 μm, the pressure in the pressure reductionchamber is maintained, and a second solution 503 in which photo acidgenerating materials such as sulfonate are dissolved in the solventstarts to be introduced into the pressure reduction chamber. It has beenconfirmed that the second solution 503 is sprayed as mist onto theliquid film 502 a surface in the pressure reduction chamber. After theelapse of 30 seconds, the pressure reduction chamber is opened and thesubstrate is removed. Note that a numeral number 511 denotes alower-layer film from which the solvent is removed and which includesSiO₂ and SiOCH₃.

As shown in FIG. 48C, the thickness of a silica glass film 510 formed byremoving the solvent was 0.3 μm. As a result of physicochemicalanalysis, it has been confirmed that the acid generating material isincluded in an upper-layer film 512 in a range of 20 nm from the filmsurface.

Subsequently, as shown in FIG. 48D, a chemical amplification type resistfilm 520 is formed on the silica glass film 510. The chemicalamplification type resist film 520 is successively subjected topre-exposure baking and cooling. Thereafter, with respect to thechemical amplification type resist film 520, the predetermined patternis exposed. After exposure, post-exposure baking and cooling areperformed.

Subsequently, as shown in FIG. 48E, the chemical amplification typeresist film 520 is developed to form a resist pattern 521.

For the silica glass film 510 prepared according to the presentembodiment, since the photo acid generating material is distributed inthe upper-layer film 512 of the surface, the above-described problem canbe solved. Even when the film is coated with the chemical amplificationtype resist, exposed, and developed to prepare the device pattern, aresist process superior in dimensional uniformity can be performedwithout any opening defect.

The present invention is superior to Jpn. Pat. No. 2842909 in that theacid generation amount of silica glass as a foundation can easily beadjusted for each chemical amplification type resist film. This cansolve problems that depending on the chemical amplification type resistfilm, a slight opening defect has heretofore been generated because ofacid shortage with the use of silica glass with the same photo acidgenerating material introduced therein, and a pattern lower part becomesthin and falls because of excess acid.

Note that the actually prepared film is coated with the chemicalamplification type and exposed/developed to form the pattern, the shapeand dimension of the pattern are measured, defects are checked, andthereby the thickness and amount of a region including the photo acidgenerating material in the present embodiment may be optimized.

NINTH EMBODIMENT

A solid film forming method according to the present embodiment will bedescribed with reference to the process sectional views of FIGS. 49A to49C. FIGS. 49A to 49C are the process sectional views showing themanufacturing processes of the semiconductor apparatus according to aninth embodiment of the present invention.

First, as shown in FIG. 49A, a liquid film 602 including the resistsolution is formed on a substrate 601 which includes a 1 μm steppedportion and whose area ratio of a convex portion to a concave portion is1:1. At the forming time of the liquid film 602, the liquid film isformed so that a thickness h of the liquid film 602 is larger than 10.5μm. In the present embodiment, the liquid film 602 was formed so as toset an average height to 15 μm.

The liquid film 602 is formed using the liquid film forming apparatusdescribed in the sixth embodiment and shown in FIG. 42. As a concretecondition, on the substrate fixed onto the stage, the solution dischargenozzle (φ40 μm) is reciprocated/moved by the nozzle driving unit in thecolumn-direction at a speed of 1 m/s. When the solution discharge nozzleis positioned outside the substrate, the stage is successively moved bythe stage driving unit at a pitch of 0.3 mm in the row-direction, andthe resist solution (solid content of 3.0%) is linearly discharged toform the liquid film 602.

Note that to adjust the thickness of the liquid film 602, any one of thesolid content in the solution, relative movement pitch of the substrateand solution discharge nozzle, relative movement speed, and dischargeamount of the solution is controlled.

Subsequently, as shown in FIG. 49B, the substrate 601 on whose surfacethe liquid film 602 is formed is sealed in the treatment containerfilled with the atmosphere of the solvent for 60 seconds, and the liquidfilm 602 surface is leveled (flatted).

Next, as shown in FIG. 49C, the solvent in the liquid film 602 isremoved, and a resist film 603 including the solid content in the liquidfilm 602 is formed. One example of the removal of the solvent in theliquid film 602 will be described hereinafter. The substrate iscontained in a pressure reduction drying treatment unit including aninfrared irradiation portion shown in FIG. 50, and the treatmentcontainer is exhausted at a pressure reduction speed of −100 Torr/sec.When the pressure in a treatment container 611 reaches 2 Torr as thevapor pressure of the solvent in the liquid film, the liquid film 602 onthe substrate 601 is irradiated with infrared rays from an infraredirradiation portion 612. Note that an infrared wavelength is set to arange of 2.5 to 3.0 μm including a wavelength to be absorbed by thesolvent of a coat liquid for use. The whole substrate surface isirradiated with the infrared rays through a quartz window 613 from theoutside of the treatment container 611. By the pressure reduction effectand the heating by the infrared rays, the solvent in the liquid film 602is rapidly vaporized, and the resist film 603 constituted of the solidcontent included in the solution is formed on the substrate 601 in twoseconds.

The film thickness distribution of the coat film which is formed by theabove-described process and which includes a 1.0 μm stepped portion onthe substrate is shown in FIG. 51A. As shown in FIG. 51A, the thicknessof the resist film 603 formed in the concave portion of the substrate601 was 0.465 μm, and the thickness of the resist film 603 formed in theconvex portion was 0.435 μm. A difference in the thickness between thecoat films formed on the concave and convex portions is about 7% withrespect to an average film thickness of 0.450 μm and the coat film canthus be formed along the substrate surface with good uniformity.

Two samples including liquid films having different film thicknesseswere formed in a method different from the above-described film formingmethod, and were compared with the resist film formed in the methoddescribed in the present embodiment. Additionally, the solid content inthe solution was changed so that the average value of the filmthicknesses of the resist films in the concave and convex portionsformed in two samples was 0.450 μm, in the same manner as in the resistfilm formed in the above-described method.

Sample B: formed using a resist solution including a solid content of6.4% so that the average height of the liquid film is 7 μm.

Sample C: formed using the liquid film of the resist solution includinga solid content of 9% so that the average height of the liquid film is 5μm.

The film thickness distributions of the coat films in the respectivesamples B, C are shown in FIGS. 51B, 51C. With the sample B, the filmthickness of the concave portion of a resist film 603′ was 0.48 μm, andthe film thickness of the convex portion of the resist film 603′ was0.416 μm. The film thickness difference with respect to the average filmthickness of 0.45 μm deteriorated at about 14%. With the sample C, thefilm thickness of the concave portion of a resist film 603″ was 0.495μm, and the film thickness of the convex portion of the resist film 603″was 0.405 μm. The film thickness difference with respect to the averagefilm thickness of 0.45 μm greatly deteriorated at about 20%.

The above-described results are shown in a graph of FIG. 52. As shown inFIG. 52 and as described above, the coat film can uniformly (filmthickness difference within 10%) be formed along the concave/convexportion on the concave/convex substrate only with the sample using thepresent method. Note that FIG. 52 shows the sample formed in the methoddescribed in the present embodiment as the sample A.

The effect of the present invention will next be described.

By the above-described coating method, the liquid film is formed on thesubstrate including the stepped portion at a ratio of the concaveportion to the convex portion, which is 1:1. Thereafter, the liquid filmflows into the concave portion from the convex portion by the fluidityof the liquid film and is smoothed. Therefore, after the leveling step,there is no stepped portion in the concave/convex portion in the liquidfilm surface (FIG. 49B). Therefore, when the solvent is rapidlyvaporized from the liquid film in this state, each solid film thicknessformed in the concave/convex portion in a unit area of the solid contentis represented by the following equations (12), (13):

$\begin{matrix}\frac{\left( {h + {0.5d}} \right){p \cdot c_{L}}}{c_{S}} & (12) \\\frac{\left( {h - {0.5d}} \right){p \cdot c_{L}}}{c_{S}} & (13)\end{matrix}$

h: average liquid film thickness

d: stepped portion height

p: solid content (ratio)

c_(S): density of the liquid film

c_(L): density of the solid content in the solid film

A condition on which the difference of the film thicknesses of theconcave and convex portions is 10% is represented by equation (14):

$\begin{matrix}{{\frac{\left( {h + {0.5d}} \right){p \cdot c_{L}}}{c_{S}}\text{:}\frac{\left( {h - {0.5d}} \right){p \cdot c_{L}}}{c_{s}}} = {1.1\text{:}1}} & (14)\end{matrix}$

Therefore, in order to set the difference of the film thickness of theconcave/convex portion to be within 10%, the condition of equation (15)obtained by solving the equation (14) needs to be satisfied.h>10.5d  (15)

As shown in the equation (15), the average liquid film thickness needsto be larger than 10.5 times the stepped portion height.

In the above-described method, since the relation is satisfied, the filmthickness difference can be set to be within the predetermined range,and the film having a substantially uniform film thickness along thestepped portion can be obtained. Moreover, the parameters described inthe equation (15) include only shelf height and liquid thickness, andthe solid content and density in the liquid film are not used.

The concave/convex portion will be described in which a ratio of thearea of the convex portion to the whole area is a (1>a>0), and a ratioof the area of the concave portion to the whole area is 1−a. In theleveled state, a film thickness h₁ in the concave portion and filmthickness h_(u) in the convex portion are as follows:h ₁ =h+adh _(u) =h+(a−1)d

Therefore, when the solvent is rapidly vaporized from the liquid film inthe leveled state, each solid film thickness formed in theconcave/convex portion in the unit area of the solid content isrepresented by the following equations (16), (17):

$\begin{matrix}\frac{\left( {h + {ad}} \right){p \cdot c_{L}}}{c_{S}} & (16) \\\frac{\left( {h + {\left( {a - 1} \right)d}} \right){p \cdot c_{L}}}{c_{S}} & (17)\end{matrix}$

The condition on which the difference of the film thicknesses of theconcave and convex portions is 10% is represented by equation (18):

$\begin{matrix}{{\frac{\left( {h + {ad}} \right){p \cdot c_{L}}}{c_{S}}\text{:}\frac{\left( {h + {\left( {a - 1} \right)d}} \right){p \cdot c_{L}}}{c_{S}}} = {1.1\text{:}1}} & (18)\end{matrix}$

Therefore, in order to set the difference of the film thickness of theconcave/convex portion to be within 10%, the condition of equation (19)obtained by solving the equation (18) needs to be satisfied:h>(11−a)d  (19)

As represented by the equation (19), with the concave/convex substratewhose ratio of the concave portion is a, the thickness needs to belarger than (11−a) times the stepped portion height d.

On the other hand, the resist including the solid content of 1.8% isused, and the average thickness of the concave and convex portions ofthe liquid film is set to 25 μm so that the film thickness of the solidcontent after the drying of the solvent is 0.450 μm. In this case, sincethe relation of the equation (15) is satisfied, the film thickness ofthe concave portion is 0.459 μm that of the convex portion is 0.441 μm,the film thickness difference is 4%, and the film is thus formed withhigh precision as compared with the present invention.

However, as shown in FIG. 53, as seen from the film thicknessdistribution over the whole surface of a substrate 601, it has beenconfirmed that the film thickness of a resist film 623 largelyfluctuates in substrate peripheral edge regions in the coating start andend portions, and the film thickness uniformity is largely deteriorated.This film thickness fluctuation was not seen when the film was formedwith an average liquid film thickness of 15 μm as described above.

As disclosed in Jpn. Pat. KOKAI Publication No. 2001-168021 by thepresent inventors, the reason why the film thickness fluctuation iscaused is that the flow by gravity is caused with a liquid thickness notless than the thickness which can be supported by the substrate. FIG. 54shows dependence of fluidity in edge portions on the liquid filmthickness. It is seen that the fluidity rapidly increases with thethickness exceeding 20 μm. FIG. 55 shows the dependence of the filmthickness uniformity of the convex portion in the whole substratesurface on the liquid film thickness. The drawings also show the filmprepared with a liquid thickness of 22 μm. It is seen from FIGS. 54, 55that the film thickness uniformity is correlated with fluidity and thefilm thickness uniformity rapidly deteriorated at a boundary of 20 μm.As described above, also in the present invention method, in order toobtain the uniform coat film over the whole concave/convex substratesurface, it is preferable to satisfy the equation (19) and to set theliquid film thickness to be less than 20 μm.

As described above, for the film forming method described in the presentembodiments, various conditions can be changed. The liquid film formingmethod is not limited to the above-described coating or spiral coatingmethod. Moreover, the present method can also be applied to the liquidfilm prepared in various methods such as a method of discharging orspraying the solution to form the film, and a method of using themeniscus phenomenon to form the film as disclosed in Jpn. Pat. Appln.KOKAI Publication Nos. 2-220428, 6-151295, 7-321001, 2001-310155, and11-243043.

Moreover, the drying method is not limited to the present inventionmethod. For example, a baking method of heating/drying the substratedirectly with a hot plate, air-current drying method, and the like mayalso be used. Additionally, the conditions can be changed as long as theconditions do not run counter to the scope of the present invention.

Note that the present invention is not limited to the above-describedembodiments, and can variously modified and carried out withoutdeparting from the scope.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1. A film forming method comprising: forming a liquid film including asolid content and solvent on a substrate; starting a drying treatment toremove the solvent in the liquid film; supplying a gas including asolvent to a surface of the liquid film; measuring flatness of thesurface of the liquid film during the drying treatment; controlling atleast one of a concentration of the solvent included in the gas and atemperature of the substrate based on the measured flatness during thedrying treatment to enhance the flatness; and ending the dryingtreatment to form a solid film including the solid content on thesubstrate.
 2. The film forming method according to claim 1, wherein themeasuring of the flatness of the liquid film comprises: measuring a filmthickness of the liquid film in a plurality of positions on thesubstrate; and the enhancing of the flatness comprises: setting themeasured film thicknesses to be equal to one another.
 3. The filmforming method according to claim 2, wherein the measurement positionsof the film thickness include at least a middle portion and peripheraledge of the substrate.
 4. The film forming method according to claim 3,further comprising: setting a vaporized amount of the solvent from theliquid film of the middle portion of the substrate to be larger thanthat of the solvent from the liquid film of the peripheral edge of thesubstrate, when the measured film thickness of the middle portion islarger than that of the peripheral edge.
 5. The film forming methodaccording to claim 4, further comprising: setting the temperature of theperipheral edge of the substrate to be lower than that of the middleportion of the substrate.
 6. The film forming method according to claim3, wherein the enhancing of the flatness comprises: setting a vaporizedamount of the solvent from the liquid film of the middle portion of thesubstrate to be smaller than that of the solvent from the liquid film ofthe peripheral edge of the substrate, when the measured film thicknessof the middle portion is smaller than that of the peripheral edge. 7.The film forming method according to claim 6, wherein the controlling ofthe temperature of the substrate comprises: setting the temperature ofthe peripheral edge of the substrate to be higher than that of themiddle portion of the substrate.
 8. The film forming method according toclaim 1, wherein a flow rate of the gas is increased with respect to atime.
 9. The film forming method according to claim 1, furthercomprising: performing the drying treatment of the liquid film formed ona test substrate in a plurality of conditions in which the atmosphere inthe container and the temperature of the substrate are changed;measuring the film thicknesses of the liquid film in a center portionand peripheral edge of each test substrate; and setting a condition towhich a difference of the film thickness between the center portion andperipheral edge is small as the condition of the drying treatment. 10.The film forming method according to claim 2, wherein the liquid filmcontains a solid content of an organic base, inorganic base, or metalbase in the solvent.